U.S. patent number 7,062,092 [Application Number 09/682,071] was granted by the patent office on 2006-06-13 for system, method, and computer software product for gain adjustment in biological microarray scanner.
This patent grant is currently assigned to Affymetrix, Inc.. Invention is credited to Shantanu V. Kaushikkar, Eric E. McKenzie, John C. Stephens, Nathan K. Weiner.
United States Patent |
7,062,092 |
Kaushikkar , et al. |
June 13, 2006 |
System, method, and computer software product for gain adjustment
in biological microarray scanner
Abstract
Systems, methods, and computer program products are described
for adjusting the gain of a scanner. The scanner includes one or
more excitation sources, an emission detector having a first gain,
and a variable gain element having a second gain. One described
method includes receiving a user-selected gain value, adjusting the
first gain based on a first portion of the user-selected gain
value, and adjusting the second gain based on a second portion of
the user-selected gain value. Another described method includes
selecting an auto-gain value, adjusting the first gain based on a
first portion of the auto-gain value, adjusting the second gain
based on a second portion of the auto-gain value, causing the
scanner to collect sample pixel intensity values, determining a
comparison measure based on comparing the sample pixel intensity
values to desired pixel intensity values, and adjusting the
auto-gain value based on the comparison measure.
Inventors: |
Kaushikkar; Shantanu V. (San
Jose, CA), Weiner; Nathan K. (Stoughton, MA), McKenzie;
Eric E. (Malden, MA), Stephens; John C. (Boulder Creek,
CA) |
Assignee: |
Affymetrix, Inc. (Santa Clara,
CA)
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Family
ID: |
26921061 |
Appl.
No.: |
09/682,071 |
Filed: |
July 17, 2001 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20020168094 A1 |
Nov 14, 2002 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60226999 |
Aug 22, 2000 |
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60286578 |
Apr 26, 2001 |
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Current U.S.
Class: |
382/213 |
Current CPC
Class: |
G01N
27/44717 (20130101); G01N 27/44721 (20130101); G01N
21/6452 (20130101); G16B 45/00 (20190201); G16B
25/00 (20190201); B01J 2219/00596 (20130101); B01J
2219/00659 (20130101); B01J 2219/00677 (20130101); G01N
2021/6419 (20130101); B01J 2219/00527 (20130101); G01N
2035/0494 (20130101); B01J 2219/00585 (20130101); B01J
2219/00695 (20130101); B01J 2219/00605 (20130101); G01N
2021/6471 (20130101); G01N 2021/6441 (20130101); B01J
2219/00533 (20130101); B01J 2219/00612 (20130101); B01J
2219/00689 (20130101); G01N 2021/6421 (20130101); B01J
2219/00707 (20130101); B01J 2219/00702 (20130101); B01J
2219/00675 (20130101); G01N 2035/00158 (20130101); C40B
50/14 (20130101) |
Current International
Class: |
G06K
9/74 (20060101) |
Field of
Search: |
;382/312 ;341/139
;348/255,229.1,230.1,231.99 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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39 15 692 |
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Nov 1990 |
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DE |
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WO 99/47964 |
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Sep 1999 |
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WO |
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Other References
Axon Instruments, Inc. Press Release dated Mar. 8, 2000 entitled,
"Axon Instruments Announces Release of GenePix Pro 3.0",
http://www.axon.com/press/pr20000308.htm. cited by other .
GenePix Pro 3.0 Software,
http://www.apbiotech.com/application/miroarray/GenePix_Pro3.htm.
cited by other .
Khan J. et al.; "DNA Microarray Technology: the anticipated impact
on the study of human disease"; BIOCHIMICA ET BIOPHYSICA ACTA,
Amsterdam, NL; vol. 1423, No. 2; Mar. 25, 1999; pp. M17-M28. cited
by other .
Xiang C. C.; "cDNA Microarry Technology and its Applications";
BIOTECHNOLOGY ADVANCES, Elsevier Publishing, Barking GB; vol. 18,
No. 1; Mar. 2000; pp. 35-46. cited by other .
Cortese J. D.; "Array of Options: Instrumentation to Exploit the
DNA Microarray Explosion"; SCIENTIST, Institute for Scientific
Information, US; vol. 14, No. 11; May 29, 2000; pp. 1-4. cited by
other .
Bowtell D. D. L.; "Options Available-From Start to Finish-For
Obtaining Expression Data by Microarray"; NATURE GENETICS, NY, NY,
US; vol. 21, No. SUPPL; Jan. 1999; pp. 25-32. cited by
other.
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Primary Examiner: Couso; Jose L.
Attorney, Agent or Firm: McCarthy, III; William R
McGarrigle; Philip L. Sharr; Alan B.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
The present application relates to and claims priority from U.S.
Provisional Patent Application Ser. No. 60/226,999, titled "System,
Method, and Product for Linked Window Interface," filed Aug. 22,
2000, and U.S. Provisional Patent Application Ser. No. 60/286,578,
titled "System, Method, and Product for Scanning of Biological
Materials," filed Apr. 26, 2001, which are hereby incorporated
herein by reference in their entireties for all purposes. The
present application also relates to U.S. patent application Ser.
No. 09/682,074 entitled System, Method, and Computer Program
Product for Specifying a Scanning Area of a Substrate, and to U.S.
patent application Ser. No. 09/682,076 entitled System, Method, and
Computer Software Product for Grid Alignment of Multiple Scanned
Images, both of which are filed concurrently herewith and are
hereby incorporated herein by reference in their entireties for all
purposes.
Claims
What is claimed is:
1. A computer program product for adjusting the gun of a scanner
having one or more excitation sources, an emission detector having
a first gain, and a variable gain element having a second gain,
wherein the computer program product, when executed on a computer
system, performs a method comprising the steps of: (a) providing a
first user interface constructed and arranged to enable a user to
select a user-selected gain value; (b) receiving the user-selected
gain value, (c) adjusting the first gain based, at least in part,
on a first portion of the user-selected gain value; and (d)
adjusting the second gain based, at least in part, on a second
portion of the user-selected gain value.
2. The computer program product of claim 1, wherein: step (c)
includes the steps of (i) determining the first portion to be equal
to a no-change value when the user-selected gain value is equal to
or less than a threshold value, and (ii) determining the first
portion to be equal to an excess of the user-selected gain value
over the threshold value, when the user-selected gain value is
greater than the threshold value; and step (d) includes the steps
of (i) determining the second portion to be equal to the
user-selected gain value when the user-selected gain value is equal
to or less than a threshold value, and (ii) determining the second
portion to be equal to the threshold value when the user-selected
gain value is equal to or greater than the threshold value.
3. The computer program product of claim 2, wherein: the threshold
value is predetermined.
4. The computer program product of claim 1, wherein: step (c)
includes the steps of (i) determining the first portion to be equal
to the user-selected gain value when the user-selected gain value
is equal to or less than a threshold value, and (ii) determining
the first portion to be equal to the threshold value when the
user-selected gain value is equal to or greater than the threshold
value: and step d) includes the steps of (i) determining the second
portion to be equal to a no-change value when the user-selected
gain value is equal to or less than a threshold value, and (ii)
determining the second portion to be equal to an excess of the
user-selected gain value over die threshold value, when the
user-selected gain value is greater than the threshold value.
5. The computer program product of claim 4, wherein: the threshold
value is predetermined.
6. The computer program product of claim 1, wherein the method
further comprises the step of: (e) receiving a calibration gain for
a first of the one or more excitation sources, wherein the
calibration gain is based, at least in part, on an output of the
emission detector responsive to the first excitation source
exciting a calibration source; and (f) adjusting the first gain,
the second gain, or both based, at lent in part, on the calibration
gain.
7. The computer program product of claim 6, wherein: the
calibration gain is based on a measurement that depends, at least
in part, on the output of the emission detector.
8. The computer program product of claim 1, wherein: the first user
interface further is constructed and arranged to enable the user to
associate the user-selected gain value with a first of the one or
more excitation sources; step (b) further includes receiving from
the first user interface the association of the user-selected gain
value with the first excitation source; and steps (c) and (d) are
done when the first excitation source is operational.
9. The computer program product of claim 8, wherein: the user
associates the user-selected gain value with the first excitation
source based, at least in part, on identifying a scanning operation
in which the first excitation source is operational.
10. The computer program product of claim 1, wherein: the first
user interface further is constructed and arranged to enable the
user to associate the user-selected gain value with a first of one
or more emission labels; step (b) further includes receiving from
the first user interface the association of the user-selected gain
value with the first emission label; and steps (c) and (d) are done
when the first emission label is excited in a scanning
operation.
11. The computer program product of claim 1, wherein: the method
further comprises the step of (e) providing a second user interface
constructed and arranged to enable a user to initiate a scanning
operation; and stop (b) further comprises the steps of (i)
receiving the user-selected gain value from the first user
interface and storing the user-selected gain value in a memory
storage unit, and (ii) retrieving the user-selected gain value from
the memory storage unit responsive to the user initiating a
scanning operation.
12. The computer program product of claim 1, wherein: the first and
second user interfaces are included in a same user interface.
13. The computer program product of claim 1, wherein: the emission
detector includes a photomultiplier tube.
14. The computer program product of claim 1, wherein: the first
gain amplifies an emission signal based, at least in part, on
emissions from an emission label spatially associated with a probe
of a probe array.
15. The computer program product of claim 14, wherein: the probe
array is a spotted probe array.
16. The computer program product of claim 14, wherein: the probe
array is a synthesized probe array.
17. A computer program product for adjusting the gain of a scanner
having one or more excitation sources, an emission detector having
a first gain, and a variable gain element having a second gain,
wherein the computer program product, when executed on a computer
system, performs a method comprising the steps of: (a) receiving
one or more user-selected gain values from one or more ranges of
gain values; (b) adjusting the first gain based at least in part,
on a first of the one or more user-selected gain values; and (c)
adjusting the second gain based, at least in part, on a second of
the one or more user-selected gain values.
18. The computer program product of claim 17, wherein the method
further comprises the steps of: (d) receiving a calibration gain
for a first of the one or more excitation sources, wherein the
calibration gain is based, at least in part, on an output of the
emission detector responsive to the first excitation source
exciting a calibration source; and (e) adjusting the first gain,
the second gain, or both based, at least in part, on the
calibration gain.
19. The computer program product of claim 17, wherein: the user
interface further is constructed and arranged to enable the user to
associate the first user-selected gain value with a first of the
one or more excitation sources; stop (a) further includes receiving
from the user interface the association of the first user-selected
gain value with the first excitation source; and steps (b) and (c)
are done when the first excitation source is operational.
20. A computer program product for adjusting the gain of a scanner
having one or more excitation sources, an emission detector having
a first gain, and a variable gain element having a second gain,
wherein the computer program product, when executed on a computer
system, performs a method comprising the steps of: (a) receiving a
user-selected gain value; (b) adjusting the first gain based, at
least in part, on a first portion of the user-selected gain value,
including the steps of (i) determining the first portion to be
equal to a no-change value when the user-selected gain value is
equal to or less than a threshold value, and (ii) determining the
first portion to be equal to an excess of the user-selected gain
value over the threshold value, when the user-selected gain value
is greater than the threshold value; (c) adjusting the second gain
based, at least in part, on a second portion of the user-selected
gain value; (d) receiving a calibration gain for a first of the one
or more excitation sources, wherein the calibration gain is based,
at least in part, on an output of the emission detector responsive
to the first excitation source exciting a calibration source; and
e) adjusting the first gain, the second gain, or both based, at
least in part, on the calibration gain.
21. A gain adjustment system, comprising: (a) a scanner having (i)
one or more excitation sources, (ii) an emission detector having a
fist gain, and (iii) a variable gain element having a second gain;
(b) a computer-implemented user interface constructed and arranged
to enable a user to select a user-selected gain value; and c)
scanner control and analysis control logic comprising (i) a
user-selected gain data manager constructed and arranged to receive
the user-selected gain value, and (ii) a scan gain controller
constructed and arranged to adjust the first gain based, at least
in part, on a first portion of the user-selected gain value, and to
adjust the second gain based, at least in part, on a second portion
of the user-selected gain value.
22. The system of claim 21, wherein: the scan gain controller
further is constructed and arranged to determine the second portion
to be equal to the user-selected gain value, and the first portion
to be a no-change value, when the user-selected gain value is equal
to or less than a threshold value; and to determine the second
portion to be equal to the user-selected gain value, and the first
portion to be equal to an excess of the user-selected gain value
over the threshold value, when the user-selected gain value is
greater than the threshold value.
23. The system of claim 21, wherein: the scan gain controller
further is constructed and arranged to determine the first portion
to be equal to the user-selected gain value, and the second portion
to be a no-change value, when the user-selected gain value is equal
to or less than a threshold value; and to determine the first
portion to be equal to the user-selected gain value, and the second
portion to be equal to an excess of the user-selected gum value
over the threshold value, when the user-selected gain value is
greater than the threshold value.
24. The system of claim 21, wherein: the scan gain controller
further is constructed and arranged to receive a calibration gain
for a first of the one or more excitation sources, wherein the
calibration gain is based, at least in part, on an output of the
emission detector responsive to the first excitation source
exciting a calibration source; and to adjust the first gain, the
second gain or both based, at least in part, on the calibration
gain.
25. A method for adjusting the gain of a scanner having one or more
excitation sources, an emission detector having a first gain, and a
variable gain element having a second gain, comprising the steps
of: (a) receiving a user-selected gain value; (b) adjusting the
first gain based, at least in part, on a first portion of the
user-selected gain value; and (c) adjusting the second gain based,
at least in part, on a second portion of the user-selected gain
value.
26. The method of claim 25, wherein: steps (b) and (c) include the
step of allocating the user-selected gain between the flint and
second portions based, at least in part, on one or more operational
characteristics of the emission detector.
27. The method of claim 26, wherein: the operational
characteristics include signal to noise ratio.
28. A computer program product for adjusting the gain of a scanner
having one or more excitation sources, an emission detector having
a first gain, and a variable gain element having a second gain,
wherein the computer program product, when executed on a computer
system, performs a method comprising the steps of: (a) selecting an
auto-gain value; (b) adjusting the first gain based, at least in
part, on a first portion of the auto-gain value; (c) adjusting the
second gain based, at least in part, on a second portion of the
auto-gain value; (d) causing the scanner to collect a plurality of
sample pixel intensity values using the adjusted first and second
gains; e) determining a comparison measure based on comparing one
or more of the plurality of sample pixel intensity values to one or
more of a plurality of desired pixel intensity values; and (f)
adjusting the auto-gain value based on the comparison measure.
29. The computer program product of claim 28, wherein; steps (b)
through (f) are repeated until the comparison measure reaches an
acceptance value or range, or until a number of repetitions exceeds
an attempt number.
30. The computer program product of claim 29, wherein: the
acceptance value or range, the attempt number, or both are user
selected.
31. The computer program product of claim 29, wherein: the
acceptance value or range, the attempt number, or both are
predetermined.
32. The computer program product of claim 29, wherein: the
acceptance value or range, the attempt number, or both are
calculated.
33. The computer program product of claim 28, wherein: the
comparison measure includes a histogram of the plurality of sample
pixel intensity values.
34. The computer program product of claim 33, wherein: the
comparison measure includes a ratio between a first portion of the
plurality of sample pixel intensity values in a first number of
bins of the histogram and a second portion of the plurality of
sample pixel intensity values in a second number of bins of the
histogram.
35. The computer program product of claim 28, wherein: the
comparison measure includes a statistical measure.
36. The computer program product of claim 35, wherein: the
statistical measure includes a mean or average of two or more of
the plurality of sample pixel intensity values.
37. The computer program product of claim 28, wherein: the first
gain amplifies an emission signal based, at least in part, on
emissions from an emission label spatially associated with a probe
of a probe array; and
38. The computer program product of claim 37, wherein: the probe
array is a spotted probe array.
39. The computer program product of claim 37, wherein: the probe
array is a synthesized probe array.
40. The computer program product of claim 31, wherein: the
plurality of desired pixel intensity values is determined based, at
least in part, on an expected ratio of background pixels on the
probe array to probe pixels on the probe array.
41. The computer program product of claim 28, wherein: step (b)
includes the steps of (i) determining the first portion to be equal
to a no-change value when the auto-gain value is equal to or less
than a threshold value, and (ii) determining the first portion to
be equal to an excess of the auto-gain value over the threshold
value, when the auto-gain value is greater than the threshold
value; and step (c) includes the steps of (i) determining the
second portion to be equal to the auto-gain value when the
auto-gain value is equal to or less than a threshold value, and
(ii) determining the second portion to be equal to the threshold
value when the auto-gain value is equal to or greater than the
threshold value.
42. The computer program product of claim 41, wherein: the
threshold value is predetermined.
43. The computer program product of claim 28, wherein the method
further comprises the step of: (g) receiving a calibration gain for
a first of the one or more excitation sources, wherein the
calibration gain is based, at least in part, on an output of the
emission detector responsive to the first excitation source
exciting a calibration source; and (h) adjusting the first gain,
the second gain, or both based, at least in part, on the
calibration gain.
44. The computer program product of claim 28, wherein: the emission
detector includes a photomultiplier tube.
45. A gain adjustment system, comprising: (a) a scanner having (i)
one or more excitation sources, (ii) an emission detector having a
first gain, and (iii) a variable gain element having a second gain;
and (b) scanner control and analysis control logic comprising a
scan gain controller constructed and arranged to (i) select an
auto-gain value, (ii) adjust the first gain based, at least in
part, on a first portion of the auto-gain value; (iii) adjust the
second gain based, at least in part, on a second portion of the
auto-gain value; (iv) cause the scanner to collect a plurality of
sample pixel intensity values using the adjusted first and second
gains; (v) determine a comparison measure based on comparing one or
more of the plurality of sample pixel intensity values to one or
more of a plurality of desired pixel intensity values; and (vi)
adjust the auto-gain value based on the comparison measure.
46. A method for adjusting the gain of a scanner having one or more
excitation sources, an emission detector having a first gain, and a
variable gain element having a second gain, comprising the steps
of: (a) selecting an auto-gain value; (b) adjusting the first gain
based, at least in part, on a first portion of the auto-gain value,
(c) adjusting the second gain based, at least in part, on a second
portion of the auto-gain value; (d) causing the scanner to collect
a plurality of sample pixel intensity values using the adjusted
first and second gains; (e) determining a comparison measure based
on comparing one or more of the plurality of sample pixel intensity
values to one or more of a plurality of desired pixel Intensity
values; and (f) adjusting the auto-gain value based on the
comparison measure.
47. The method of claim 46, wherein: steps (b) and (c) include the
step of allocating the auto-gain between the first and second
portions based, at least in part, an one or more operational
characteristics of the emission detector.
48. The method of claim 47, wherein: the operational
characteristics include signal to noise ratio.
Description
COPYRIGHT STATEMENT
A portion of the disclosure of this patent document contains
material that is subject to copyright protection. The copyright
owner has no objection to the facsimile reproduction by anyone of
the patent document or the patent disclosure as it appears in the
Patent and Trademark Office patent file or records, but otherwise
reserves all copyright rights whatsoever.
BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to systems, methods, and products for
scanning arrays of biological materials and, more particularly, for
amplifying, analyzing, and displaying information obtained from
scanning.
2. Related Art
Synthesized probe arrays, such as Affymetrix.RTM. GeneChip.RTM.
arrays, have been used to generate unprecedented amounts of
information about biological systems. For example, a commercially
available GeneChip.RTM. array set from Affymetrix, Inc. of Santa
Clara, Calif., is capable of monitoring the expression levels of
approximately 6,500 murine genes and expressed sequence tags
(EST's).
Experimenters can quickly design follow-on experiments with respect
to genes, EST's, or other biological materials of interest by, for
example, producing in their own laboratories microscope slides
containing dense arrays of probes using the Affymetrix.RTM. 417.TM.
Arrayer or other spotting devices. Analysis of data from
experiments with synthesized and/or spotted probe arrays may lead
to the development of new drugs and new diagnostic tools. In some
conventional applications, this analysis begins with the capture of
fluorescent signals indicating hybridization of labeled target
samples with probes on synthesized or spotted probe arrays. The
devices used to capture these signals often are referred to as
scanners, an example of which is the Affymetrix.RTM. 428.TM.
Scanner from Affymetrix, Inc. of Santa Clara, Calif. There is a
great demand in the art for methods for organizing, accessing and
analyzing the vast amount of information collected by scanning
microarrays. Computer-based systems and methods have been developed
to assist a user to visualize the vast amounts of information
generated by the scanners. These commercial and academic software
applications typically provide such information as intensities of
hybridization reactions or comparisons of hybridization reactions.
This information may be displayed to a user in graphical form.
SUMMARY OF INVENTION
In accordance with some embodiments of the present invention, a
computer program product is described for adjusting the gain of a
scanner. The scanner includes one or more excitation sources, an
emission detector having a first gain, and a variable gain element
having a second gain. The computer program product, when executed
on a computer system, performs a method including: (a) providing a
user interface that enables a user to select a gain value; (b)
receiving the user-selected gain value; (c) adjusting the first (or
second) gain based, at least in part, on a first portion of the
user-selected gain value; and (d) adjusting the second (or first)
gain based, at least in part, on a second portion of the
user-selected gain value. The word adjusting in this context
includes increasing, decreasing, or leaving unchanged. The word
gain includes amplification of a signal (i.e., a positive gain) and
reduction of a signal (i.e., a gain less than one).
In some implementations of these embodiments, step (c) includes (i)
determining the first portion to be equal to a no-change value when
the user-selected gain value is equal to or less than a threshold
value, and (ii) determining the first portion to be equal to an
excess of the user-selected gain value over the threshold value,
when the user-selected gain value is greater than the threshold
value. Also in these implementations, step (d) includes the steps
of (i) determining the second portion to be equal to the
user-selected gain value when the user-selected gain value is equal
to or less than a threshold value, and (ii) determining the second
portion to be equal to the threshold value when the user-selected
gain value is equal to or greater than the threshold value. The
term no-change value means a value indicating that no change should
be made to the associated gain, i.e., the first gain in these
implementations. The threshold value may be predetermined.
One advantage of using this computer program product is that the
user simply provides a gain value, which may be a single value, and
the product allocates the user-selected gain between the emission
detector and the variable gain element. That is, in some
implementations, this allocation may be made without user
involvement. In addition to simplifying the procedure for the user,
this arrangement provides the user-selected gain while optimizing
the signal to noise ratio achieved at all gain settings. For
example, this optimization may be achieved because the program
allocates gain based on the operational characteristics of the
emission detector. In some emission detectors, for instance, the
signal to noise ratio may be good at low gain settings but decline
at higher gains. In such circumstances, the computer program
product may allocate a first portion of a user-selected gain to be
implemented by the variable gain element, such as a variable gain
amplifier, that has good signal to noise performance over this
first range of gains. If the user selects a gain that requires
amplification outside of this first range, the computer program
product allocates the additional portion of the user-selected gain
(e.g., an amount greater than a threshold value based on the upper
limit of the first range) to be implemented by the emission
detector. The signal to noise ratio of the emission detector thus
remains high because the detector is not pushed into its less
desirable higher-gain range of operations. In typical applications,
the performance characteristics of the emission detector and the
variable gain element with respect to signal to noise at various
gains are known by the scanner manufacturer. In these applications,
the threshold level at which the computer program product allocates
additional gain to be delivered by the emission detector may be a
predetermined level, i.e., determined by the computer program
product based on a data value in a look up table or in accordance
with another conventional technique. In alternative
implementations, the user may select the threshold value.
In some implementations, the method performed by the computer
program product may further include (e) receiving a calibration
gain for a first of the one or more excitation sources. The
calibration gain may be based, at least in part, on an output of
the emission detector responsive to the first excitation source
exciting a calibration source. In these implementations, the method
also includes (f) adjusting the first gain, the second gain, or
both based, at least in part, on the calibration gain.
In yet other implementations, the user interface further enables
the user to associate the user-selected gain value with a first of
one or more emission labels. Step (b) in these implementations
includes receiving from the user interface the association of the
user-selected gain value with the first emission label. Steps (c)
and (d) are done when the first emission label is excited in a
scanning operation. The method also includes, in other
implementations, the additional step of (e) providing a second user
interface that enables a user to initiate a scanning operation. In
these implementations, step (b) includes (i) receiving the
user-selected gain value from the first user interface and storing
the user-selected gain value in a memory storage unit, and (ii)
retrieving the user-selected gain value from the memory storage
unit responsive to the user initiating a scanning operation. The
first and second user interfaces may be the same interface, or may
be included as elements of a common, i.e., the same, user
interface.
In other embodiments, a computer program product for adjusting the
gain of a scanner is described that, when executed on a computer
system, performs a method including (a) receiving one or more
user-selected gain values from one or more ranges of gain values
(e.g., from one or more slide bars or other user-selectable
graphical elements); (b) adjusting the gain of an emission detector
of the scanner based, at least in part, on a first of the one or
more user-selected gain values (e.g., a slide bar for control of
the emission detector gain); and (c) adjusting the gain of a
variable gain element of the scanner based, at least in part, on a
second of the one or more user-selected gain values (e.g., a slide
bar for control of the gain of the variable gain element). The
method may also include (d) receiving a calibration gain for a
first of the one or more excitation sources, wherein the
calibration gain is based, at least in part, on an output of the
emission detector responsive to the first excitation source
exciting a calibration source; and (e) adjusting the first gain,
the second gain, or both based, at least in part, on the
calibration gain.
A gain adjustment system in accordance with other embodiments is
described. The system includes a scanner that has one or more
excitation sources, an emission detector having a first gain, and a
variable gain element having a second gain. Also included in the
system is a computer-implemented user interface that enables a user
to select a user-selected gain value. Also included in the system
is scanner control and analysis control logic comprising(i) a
user-selected gain data manager that receives the user-selected
gain value, and a scan gain controller that adjusts the first gain
based, at least in part, on a first portion of the user-selected
gain value, and that adjusts the second gain based, at least in
part, on a second portion of the user-selected gain value.
In accordance with yet other embodiments, a method is described for
adjusting the gain of a scanner. The method includes (a) receiving
a user-selected gain value; (b) adjusting the gain of an emission
detector of the scanner based, at least in part, on a first portion
of the user-selected gain value; and (c) adjusting the gain of a
variable gain element of the scanner based, at least in part, on a
second portion of the user-selected gain value.
Various embodiments are also described with respect to auto gain
operation. In one such embodiment, a computer program product
adjusts the gain of a scanner that has one or more excitation
sources, an emission detector having a first gain, and a variable
gain element having a second gain. The computer program product,
when executed on a computer system, performs a method including:
(a) selecting an auto-gain value; (b) adjusting the first gain
based, at least in part, on a first portion of the auto-gain value;
c) adjusting the second gain based, at least in part, on a second
portion of the auto-gain value; (d) causing the scanner to collect
a plurality of sample pixel intensity values using the adjusted
first and second gains; (e) determining a comparison measure based
on comparing one or more of the plurality of sample pixel intensity
values to one or more of a plurality of desired pixel intensity
values; and (f) adjusting the auto-gain value based on the
comparison measure. In these embodiments, steps (b) through (f) may
be repeated until the comparison measure reaches an acceptance
value or range, or until a number of repetitions exceeds an attempt
number. In some implementations, the comparison measure may include
a histogram of the plurality of sample pixel intensity values. The
comparison measure may also, or alternatively, include a
statistical measure.
A gain adjustment system is also described that includes a scanner
having (i) one or more excitation sources, (ii) an emission
detector having a first gain, and (iii) a variable gain element
having a second gain. The system also includes scanner control and
analysis control logic comprising a scan gain controller. The scan
gain controller (i) selects an auto-gain value, (ii) adjusts the
first gain based, at least in part, on a first portion of the
auto-gain value;(iii) adjusts the second gain based, at least in
part, on a second portion of the auto-gain value;(iv) causes the
scanner to collect a plurality of sample pixel intensity values
using the adjusted first and second gains; (v) determines a
comparison measure based on comparing one or more of the plurality
of sample pixel intensity values to one or more of a plurality of
desired pixel intensity values; and (vi) adjusts the auto-gain
value based on the comparison measure.
In yet another embodiment, a method is described for adjusting the
gain of a scanner having one or more excitation sources, an
emission detector having a first gain, and a variable gain element
having a second gain. The method includes (a) selecting an
auto-gain value; (b) adjusting the first gain based, at least in
part, on a first portion of the auto-gain value; (c) adjusting the
second gain based, at least in part, on a second portion of the
auto-gain value; (d) causing the scanner to collect a plurality of
sample pixel intensity values using the adjusted first and second
gains; (e) determining a comparison measure based on comparing one
or more of the plurality of sample pixel intensity values to one or
more of a plurality of desired pixel intensity values; and(f)
adjusting the auto-gain value based on the comparison measure.
Also described in accordance with some embodiments is a method
including: (a) receiving a user-selected gain value; (b) applying a
first gain to the emission signal based, at least in part, on a
first portion of the user-selected gain value; and (c) applying a
second gain to the emission signal based, at least in part, on a
second portion of the user-selected gain value. A further
embodiment is a method for adjusting an emission signal including:
(a) selecting an auto-gain value; (b) applying a first gain to the
emission signal based, at least in part, on a first portion of the
auto-gain value;(c) applying a second gain to the emission signal
based, at least in part, on a second portion of the auto-gain
value; (d) determining a plurality of sample pixel intensity values
based on the emission signal having applied to it the first and
second gains; (e) determining a comparison measure based on
comparing one or more of the plurality of sample pixel intensity
values to one or more of a plurality of desired pixel intensity
values; and (f) adjusting the auto-gain value based on the
comparison measure.
Also, a computer program product is described in some embodiments
that includes a gain-value receiver that receives a user-selected
gain value; a first gain controller that applies a first gain to
the emission signal based, at least in part, on a first portion of
the user-selected gain value; and a second gain controller that
applies a second gain to the emission signal based, at least in
part, on a second portion of the user-selected gain value. In other
embodiments, a computer program product includes an auto-gain value
selector; a first gain controller that applies a first gain to the
emission signal based, at least in part, on a first portion of the
auto-gain value; a second gain controller that applies a second
gain to the emission signal based, at least in part, on a second
portion of the auto-gain value; an intensity manager that
determines a plurality of sample pixel intensity values based on
the emission signal having applied to it the first and second
gains; a comparison manager that determines a comparison measure
based on comparing one or more of the plurality of sample pixel
intensity values to one or more of a plurality of desired pixel
intensity values; and an auto-gain adjuster that adjusts the
auto-gain value based on the comparison measure.
In another embodiment, a gain adjustment system is described that
includes a scanner having one or more excitation sources, an
emission detector having a first gain, and a variable gain element
having a second gain. The system also includes a scan gain
controller that adjusts the first and second gains.
The above embodiments and implementations are not necessarily
inclusive or exclusive of each other and may be combined in any
manner that is non-conflicting and otherwise possible, whether they
be presented in association with a same, or a different, aspect of
the invention. The description of one embodiment or implementation
is not intended to be limiting with respect to other embodiments or
implementations. Also, any one or more function, step, operation,
or technique described elsewhere in this specification may, in
alternative embodiments or implementations, be combined with any
one or more function, step, operation, or technique described in
the summary. Thus, the above embodiments and implementations are
illustrative rather than limiting.
BRIEF DESCRIPTION OF DRAWINGS
The above and further features will be more clearly appreciated
from the following detailed description when taken in conjunction
with the accompanying drawings. In the drawings, like reference
numerals indicate like structures or method steps and the leftmost
one or two digits of a reference numeral indicates the number of
the figure in which the referenced element first appears (for
example, the element 125 appears first in FIG. 1, the element 1110
first appears in FIG. 11). In functional block diagrams, rectangles
generally indicate functional elements, parallelograms generally
indicate data, and rectangles with a pair of double borders
generally indicate predefined functional elements. In method flow
charts, rectangles generally indicate method steps and diamond
shapes generally indicate decision elements. All of these
conventions, however, are intended to be typical or illustrative,
rather than limiting.
FIG. 1 is a simplified schematic diagram of one embodiment of
networked systems for generating, sharing, and processing probe
array data among computers on a network, including an arrayer
system for generating spotted probe arrays and scanner systems for
scanning spotted and synthesized probe arrays;
FIG. 2 is a functional block diagram of one embodiment of a user
computer of the networked computers of FIG. 1 suitable for
controlling the arrayer of FIG. 1 to produce spotted arrays;
FIG. 3A is a graphical representation of data records in one
embodiment of a data file suitable for storing data regarding
spotted arrays produced in cooperation with the user computer of
FIG. 2 and the arrayer of FIG. 1;
FIG. 3B is a graphical representation of a microscope slide
including illustrative embodiments of spotted arrays produced in
cooperation with the user computer of FIG. 2 and the arrayer of
FIG. 1;
FIG. 4 is a simplified graphical representation of selected
components of one embodiment of a scanner of FIG. 1 suitable for
scanning arrays;
FIG. 5A is a perspective view of a simplified exemplary
configuration of a scanning arm portion of the scanner of FIG.
4;
FIG. 5B is a top planar view of the scanning arm of FIG. 5A as it
scans biological features on one embodiment of a spotted array
being moved by a translation stage under the arm''s arcuate
path;
FIG. 6A is a graphical representation of one embodiment of a probe
feature showing bidirectional scanning lines such as may be
implemented using the scanning arm of FIGS. 5A and 5B;
FIG. 6B is an illustrative plot of pixel clock pulses aligned with
the scanned probe feature of FIG. 6A to show illustrative radial
position sampling points;
FIG. 6C is an illustrative plot of sampled analog emission voltages
aligned with the pixel clock pulses of FIG. 6B;
FIG. 6D is an illustrative plot of digital emission voltages
corresponding to the analog emission voltages of FIG. 6C, including
saturated values;
FIG. 7 is a functional block diagram of one embodiment of a scanner
system of FIG. 1;
FIG. 8 is a simplified functional block diagram of one embodiment
of selected elements of the scanner system of FIG. 7 comprising
illustrative gain adjustment systems;
FIG. 9 is a graphical representation of one embodiment of a
graphical user interface of the gain adjustment systems of FIG.
8;
FIG. 10 is a graphical representation of one embodiment of a
distribution of calibration and user-selected gain controls applied
to an emission detector and a variable gain element of the gain
adjustment systems of FIG. 8;
FIG. 11 is a functional block diagram of one embodiment of a
scanner control and analysis application of the gain adjustment
systems of FIG. 8;
FIGS. 12A, 12B, and 12C are flow charts of illustrative method
steps for respectively storing calibration gain data, storing
user-selected gain data, and implementing calibration and
user-selected gain adjustments;
FIG. 13 is a flow chart of illustrative method steps by which the
gain adjustment systems of FIG. 8 may determine, allocate, and
apply gains;
FIG. 14 is a flow chart showing in greater detail illustrative
method steps directed to determining an automatic gain adjustment
value, as generally shown in FIG. 13; and
FIG. 15 is a functional block diagram of one embodiment of a scan
gain controller by which the gain adjustment systems of FIG. 8 may
automatically determine, allocate, and apply gains.
DETAILED DESCRIPTION
Systems, methods, and software products to acquire, process,
analyze, and/or display data from experiments with synthesized
and/or spotted arrays are described herein with respect to
illustrative, non-limiting, implementations. Various other
alternatives, modifications and equivalents are possible. For
example, while certain systems, methods, and computer software
products are described using exemplary embodiments with reference
to spotted arrays analyzed using Affymetrix.RTM. scanners and/or
Affymetrix software, the systems, methods, and products of the
present invention are not so limited. For example, they generally
may be applied with respect to many other probe arrays, including
many types of parallel biological assays.
Probe Arrays
For example, certain systems, methods, and computer software
products are described herein using exemplary implementations for
acquiring, analyzing, and/or displaying data from arrays of
biological materials produced by the Affymetrix.RTM. 417.TM. or
427.TM. Arrayer. Other illustrative implementations are referred to
in relation to data from experiments with Affymetrix.RTM.
GeneChip.RTM. arrays. However, these systems, methods, and products
may be applied with respect to many other types of probe arrays
and, more generally, with respect to numerous parallel biological
assays produced in accordance with other conventional technologies
and/or produced in accordance with techniques that may be developed
in the future. For example, aspects of the systems, methods, and
products described herein may, in some implementations, be applied
to parallel assays of nucleic acids, PCR products generated from
cDNA clones, proteins, antibodies, or many other biological
materials. These materials may be disposed on slides (as typically
used for spotted arrays), on substrates employed for GeneChip.RTM.
arrays, or on beads, optical fibers, or other substrates, supports,
or media (all or any of which may hereafter generally and
collectively be referred to as substrates). Some implementations of
synthesized arrays, their preparation, substrates, and the like are
described in U.S. Pat. Nos. 5,744,305 and 5,445,934, which are
hereby incorporated herein by reference in their entireties for all
purposes. Moreover, with respect to some implementations in which
the context so indicates or allows, the probes need not be
immobilized in or on a substrate, and, if immobilized, need not be
disposed in regular patterns or arrays. For convenience, the term
probe array will generally be used broadly hereafter to refer to
all of these types of arrays and parallel biological assays.
For convenience, an array made by depositing or positioning
pre-synthesized or pre-selected probes on a substrate, or by
depositing/positioning techniques that may be developed in the
future, is hereafter referred to as a spotted array. Typically, but
not necessarily, spotted arrays are commercially fabricated on
microscope slides. These arrays often consist of liquid spots
containing biological material of potentially varying compositions
and concentrations. For instance, a spot in the array may include a
few strands of short polymers, such as oligonucleotides in a water
solution, or it may include a high concentration of long strands of
polymers, such as complex proteins. The Affymetrix.RTM. 417.TM. and
427.TM. Arrayers, noted above, are devices that deposit densely
packed arrays of biological material on a microscope slide in
accordance with these techniques. Aspects of these, and other, spot
arrayers are described in U.S. Pat. Nos. 6,121,048, 6,040,193 and
6,136,269, in PCT Applications Nos. PCT/US99/00730 (International
Publication Number WO99/36760) and PCT/US 01/04285, in U.S. patent
application Ser. Nos. 09/122,216, 09/501,099, and 09/862,177, and
in U.S. Provisional Patent Application Ser. No. 60/288,403, all of
which are hereby incorporated by reference in their entireties for
all purposes. Other techniques for depositing or positioning
biological probes on a substrate, i.e., creating spotted arrays,
also exist. For example, U.S. Pat. No. 6,040,193 to Winkler, et al.
is directed to processes for dispensing drops of biological
material. The ''193 patent, and U.S. Pat. No. 5,885,837 to Winkler,
also describe separating reactive regions of a substrate from each
other by inert regions and spotting on the reactive regions. The
''193 and ''837 patents are hereby incorporated by reference in
their entireties. Other techniques for producing spotted arrays are
based on ejecting jets of biological material. Some implementations
of the jetting technique use devices such as syringes or piezo
electric pumps to propel the biological material.
Spotted arrays typically are used in conjunction with tagged
biological samples such as cells, proteins, genes or EST''s, other
DNA sequences, or other biological elements. These samples,
referred to herein as targets, typically are processed so that they
are spatially associated with certain probes in the probe array. In
one non-limiting implementation, for example, one or more
chemically tagged biological samples, i.e., the targets, are
distributed over the probe array. Some targets hybridize with at
least partially complementary probes and remain at the probe
locations, while non-hybridized targets are washed away. These
hybridized targets, with their tags or labels, are thus spatially
associated with the targets'' complementary probes. The associated
probe and target may sometimes be referred to as a probe-target
pair. Detection of these pairs can serve a variety of purposes,
such as to determine whether a target nucleic acid has a nucleotide
sequence identical to or different from a specific reference
sequence. See, for example, U.S. Pat. No. 5,837,832 to Chee, et al.
Other uses include gene expression monitoring and evaluation (see,
e.g., U.S. Pat. No. 5,800,992 to Fodor, et al.; U.S. Pat. No.
6,040,138 to Lockhart, et al.; and International App. No.
PCT/US98/15151, published as WO99/05323, to Balaban, et al.),
genotyping (U.S. Pat. No. 5,856,092 to Dale, et al.), or other
detection of nucleic acids. The ''832, ''992, ''138, and ''092
patents, and publication WO99/05323,are incorporated by reference
herein in their entirety for all purposes.
To ensure proper interpretation of the term probe as used herein,
it is noted that contradictory conventions exist in the relevant
literature. The word probe is used in some contexts to refer not to
the biological material that is deposited on a substrate, as
described above, but to what has been referred to herein as the
target. To avoid confusion, the term probe is used herein to refer
to compounds such as those deposited on a substrate to create
spotted arrays.
FIG. 1 is a simplified schematic diagram of illustrative systems
for generating, sharing, and processing data derived from
experiments using probe arrays (i e., spotted arrays and/or
synthesized arrays). More particularly, an illustrative arrayer
system 148 and illustrative scanner systems 150A and 150B
(collectively, scanner systems 150) are shown. In this example,
data may be communicated among user computer 100A of system 148,
user computers 100B and 100C of systems 150, and Laboratory
Information Management (LIMS) server 120 over network 125. LIMS
server 120 and associated software generally provides data
capturing, tracking, and analysis functions from a centralized
infrastructure. Aspects of a LIMS are described in U.S. Provisional
Patent Application Nos. 60/220,587 and 60/273,231, both of which
are hereby incorporated by reference herein for all purposes. LIMS
server 120 and network 125 are optional, and the systems in other
implementations may include a scanner for spotted arrays and not
synthesized arrays, or vice versa. Also, rather than employing
separate user computers 100A and 100B to operate and process data
from an arrayer and scanner, respectively, as in the illustrated
implementation, a single computer may be used for all of these
purposes in other implementations. More generally, a large variety
of computer and/or network architectures and designs may be
employed, and it will be understood by those of ordinary skill in
the relevant art that many components of typical computer network
systems are not shown in FIG. 1 for sake of clarity.
Arrayer 120
The illustrative system of FIG. 1 includes an arrayer 120 for
producing spotted arrays, such as represented by spotted arrays
121. For example, arrayer 120 may be the Affymetrix.RTM. 417.TM. or
427.TM. Arrayer (commercially available from Affymetrix, Inc. of
Santa Clara, Calif.), elements of which are hereafter described to
provide an example of how arrayer 120 may operate in a commercial
embodiment. As noted above, however, numerous variations are
possible in the technologies and structures that may be used to
produce spotted arrays, and thus it will be understood that the
following description of arrayer 120 is merely illustrative, and is
non-limiting.
Arrayer 120 of the illustrated implementation deposits spots on
substrates consisting of standard glass microscope slides. The
slides are held on a flat platen or cartridge (not shown) that
registers the slides relative to a printing head (not shown) that
is lowered and raised to effect spotting. The spotting elements of
the printing head may include, for example, various numbers of
Affymetrix.RTM. Pin-and-Ring.TM. mechanisms, as described, e.g., in
U.S. patent application Ser. No. 09/862,177, or U.S. Provisional
Patent Application Ser. No. 60/288,403, incorporated by reference
above. For example, the printing head in illustrative
implementations may accommodate 1, 4, 8, 12, 32 or 48 pairs of pin
and ring elements to deposit the spots of biological material onto
the slide. Arrayer 120 thus may in some implementations be capable
of rapidly depositing many spots of biological fluids, such as
would be useful in preparing large numbers of DNA microarrays. The
ring of the Pin-and-Ring.TM. mechanism in one implementation
includes a circular ring section formed from a circular piece of
metal. The ring is attached at the end of an arm section that
extends from a cylinder. The pin in this example is a single,
rod-like device having at one end a very narrow tip. During
operation, the pin is inserted into and through the cylinder with
the tip being capable of moving freely through the opening of the
ring.
In some implementations, fluids to be spotted onto the microscope
slides may be stored in and retrieved from well plates (also
commonly referred to as microtiter plates) having, for example a
standard number of 96 or 348 wells. The well plates loaded with
fluids may, in some implementations, be inserted by a user into a
carousel included in arrayer 120. Arrayer 120 may include a robotic
system having an effector arm that, under computer control, may be
instructed to retrieve a well plate from the carousel. Arrayer 120
may, in some implementations, be capable of automatically
identifying well plates. For example, machine readable indicators,
e.g., bar codes, may be attached to the well plates and a bar code
reader may be attached to the robotic system for reading the bar
codes. The robotic system pivots the retrieved well plate from the
carousel to a well plate retainer on the platen. In other
implementations, a user may manually place slides on the
platen.
Arrayer 120 further includes a robotic system that may be
instructed, under computer control, to position the printing head
with respect to the well plate in the well plate retainer in order
to obtain fluids from the well plate for spotting. For example, as
described in U.S. patent application Ser. No. 09/862,177, referred
to above, rings of the printing head may be lowered into the wells
of the well plate while the pins of the printing head remain out of
contact with the fluids. The ring section is then raised out of the
fluids. Given the design of the rings, an amount of the fluid is
retained within the rings by the surface tension of the fluid and
the surface activity of the inner walls of the rings. After the
rings are raised out of the sample solution, the fluid held in each
ring forms a convex meniscus that protrudes from the bottom opening
of the ring. The printing head, including the rings with fluids,
can then be positioned at a location above a substrate (i.e.,
microscope slide in this example) onto which a fraction of the
fluid in each ring is to be deposited. The fluid volume in the ring
is sufficient to deposit or spot more than one fraction. In fact,
several hundred to a thousand or more fractions can be deposited
from a single fluid volume retained in a ring. The number of
fractions will depend on the desired volume of each fraction, the
dimensions of the pin and the viscosity of the fluid.
Once the pin and ring mechanism is position over the desired
location on the substrate, the tip of the pin is then lowered into,
through and out of the fluid retained in the ring. The surface
tension of the fluid retains the fluid within the ring while the
pin penetrates into and moves through and out of the fluid. A
fraction of the fluid is retained on the tip of the pin forming a
meniscus. The portion of the pin that passes through the ring has a
diameter that typically is small compared to the diameter of the
ring, enabling the pin to pierce the fluid without breaking the
meniscus and causing the fluid to leave the ring.
The pin with the fluid on the tip is lowered toward the surface of
the substrate until the meniscus of the fluid on the end of the pin
makes initial contact with the surface of the substrate. During
typical operation, the pin contacts the substrate without damaging
force. The fluid then adheres via surface tension to the surface of
the substrate, and as the pin is raised, the fluid is transferred
to the surface of the substrate by surface tension and gravity. The
pin is moved back through and above the fluid in the ring. The
process of sample deposition can then be repeated by repositioning
the pin and ring mechanism at another desired location above the
surface of the substrate. Alternatively, the pin and ring can be
positioned over another, different surface.
In this exemplary implementation, the printing head is positioned
on an x-y gantry that is capable of moving the printing head across
the length and width of the platen, and thus over numerous slides
retained on the platen. For example, the printing head may move in
a serpentine manner from slide to slide along a column of slides
arranged on the platen, and then back along an adjacent column of
slides on the platen. The movement of the printing head may be
controlled in accordance with various techniques such as using
sensors to count markers and arrive at a preprogrammed destination.
The printing head may optionally be directed under computer control
to wash and dry stations to clean the pins and rings between
spotting applications.
User Computer 100A
As shown in FIG. 1 and noted above, arrayer 120 operates in the
illustrated implementation under computer control, e.g., under the
control of user computer 100A. Although computer 100A is shown in
FIG. 1 for clarity as being directly coupled to arrayer 120, it may
alternatively be coupled to arrayer 120 over a local-area,
wide-area, or other network, including an intranet and/or the
Internet.
FIG. 2 is a functional block diagram showing an illustrative
implementation of computer 100A. Computer 100A may be a personal
computer, a workstation, a server, or any other type of computing
platform now available or that may be developed in the future.
Typically, computer 100A includes known components such as
processor (e.g., CPU) 205, operating system 210, system memory 220,
memory storage devices 225, graphical user interface (GUI)
controller 215, and input-output controllers 230, all of which
typically communicate in accordance with known techniques such as
via system bus 204. It will be understood by those skilled in the
relevant art that there are many possible configurations of the
components of computer 100A and that some components that may
typically be included in computer 100A are not shown, such as cache
memory, a data backup unit, and many other devices.
Input-output controllers 230 could include any of a variety of
known devices for accepting and processing information from a user,
whether a human or a machine, whether local or remote. Such devices
include, for example, modem cards, network interface cards, sound
cards, or other types of controllers for any of a variety of known
input devices. Output controllers of input-output controllers 230
could include controllers for any of a variety of known display
devices for presenting information to a user, whether a human or a
machine, whether local or remote. If one of these display devices
provides visual information, this information typically may be
logically and/or physically organized as an array of picture
elements, sometimes referred to as pixels. GUI controller 215 may
comprise any of a variety of known or future software programs for
providing graphical input and output interfaces between computer
100A and a user 201 (e.g., an experimenter wishing to use arrayer
120 to generate spotted arrays), and for processing inputs from
user 201 (hereafter sometimes referred to as user inputs or user
selections).
Arrayer Manager Application 290
Arrayer manager application 290 of the illustrated implementation
is a software application that controls functions of arrayer 120
and processes data supplied by user 201. As more particularly
described with respect to certain implementations in U.S.
Provisional Patent Application Ser. No. 60/288,403, incorporated by
reference above, application 290, when executed in coordination
with processor 205, operating system 210, and/or GUI controller
215, performs user interface functions, data processing operations,
and data transfer and storage operations. For example, with respect
to user interface functions, user 201 may employ one or more of
GUI''s 282 to specify and describe particular clones and their
location in particular wells of particular well plates. Using
another of GUI''s 282, user 201 may specify how spots of the clones
are to be arranged in arrays on one or more slides. Yet another of
GUI''s 282 may be used to operate arrayer 120, e.g., to initiate
the spotting of a number of slides without further user
participation.
As will be evident to those skilled in the relevant art,
application 290 may be loaded into system memory 220 and/or memory
storage device 225 through an input device of devices 280.
Alternatively, application 290 may be implemented as executable
instructions stored in firmware. Executable code corresponding to
application 290 is referred to as arrayer manager application
executable 290' and is shown for convenience with respect to the
illustrated implementation as stored in system memory 220. However,
instructions and data including executable instructions of
application 290, and data used or generated by it, may be located
in or shifted among other memory devices, local or remote, as
convenient for data storage, data retrieval, and/or execution.
FIG. 3A is a graphical representation of illustrative data records
in one implementation of a data file generated by arrayer manager
application executable 290'. The data file in this illustration,
referred to as array content file 292, consists of records 301,
each one of which (i.e., records 301A through 301N for any number
of N records) corresponds to one of N spots, i.e., probes, that
have been deposited, or are planned to be deposited, on spotted
arrays 121. For example, with reference to the graphical
representation of spotted arrays 121 shown in FIG. 3B, two arrays
121A and 121B (collectively, arrays 121) have been printed on
microscope slide substrate 333 by arrayer 120. Array 121A includes
probe 370A. It is assumed for purposes of illustration that data
relating to probe 370A is stored by executable 290' in probe record
301 A. In this example, each of the records in file 292 includes
the following illustrative fields: probe identifier(s) 302, probe
x-coordinate identifier(s) 304, probe y-coordinate identifier(s)
306, probe data 308, probe data links 310, pin identifier 312, well
plate identifier 316, and user-supplied data 320.
The field in record 301A labeled probe identifier(s) 302A thus, in
this example, includes certain information related to the
identification of probe 370A. For instance, field 302A may include
a name for cDNA deposited by a pin of arrayer 120 in array 121A to
produce probe 370A. In various implementations, field 302A may
also, or in addition, include a nucleotide identifier and/or a gene
symbol that identifies probe 370A. Also, field 302A may include a
build or release number of a database so that the data source used
to develop the probe can be identified. As yet another example of
information that may be included in field 302A, a probe may be
identified as either an original or as a replicate. For instance,
for quality control or other reasons, probe 370B of array 121A may
be the same probe as probe 370A, or a number of such replicate
probes may be deposited. The designation of original or replicate
number assists in comparing results from probes that are based on
the same sample. As one of ordinary skill in the relevant art will
readily appreciate, all or some of this identifying data may be
stored as a single value in field 302A (such as, for example,
concatenating name, nucleotide identifier, etc.), in separate
fields (e.g., 302A', 302A'', etc., not shown), in linked fields,
and so on as may be convenient for data storage and/or processing.
The other fields described below similarly are only representative
of many possible storage and data retrieval architectures.
Field 308A, labeled probe data in this example, may include
probe-related data such as the chromosome location of the gene or
EST represented by the probe, the band location on the chromosome,
a SNP or other type of marker that can identify the location on the
chromosome, and so on. Field 310A, labeled probe data links in this
example, similarly may include an accession number from GenBank, a
UniGene cluster number, and/or another identifier that facilitates
access to data related to probe 370A that is stored in a database.
This database may, but need not, be external to computer 100A and
accessed via network 125 and/or the Internet or other network.
Systems for providing access to such information are described, for
example, in U.S. Provisional Patent Application Ser. No.
60/288,429, hereby incorporated herein by reference in its
entirety. Field 312A of this example identifies the pin on the
print head(s) that is used to deposit probe 370A onto the slide.
This information may be useful in comparing probes deposited with
the same pin to determine, for example, if the pin is defective.
Fields 314A and 316A contain information that respectively
identifies the well plate and particular well from which biological
fluid was taken to create probe 370A. Field 320A may contain a
variety of data supplied by user 201 such as the user''s name, the
data of the experiment, and so on. It will be understood that there
are many other types of data relating to probe 370A that may be
stored, and that numerous alternative arrangements may be
implemented for storing them.
Scanner 160A: Optics and Detectors
Any of a variety of conventional techniques, or ones to be
developed in the future, may be used to generate probe-target pairs
in probe arrays that may be detected using a scanner. As one
illustrative example that will be familiar to those of ordinary
skill in the relevant art, conventional fluidics stations,
hybridization chambers, and/or various manual techniques (as, for
example, generally and collectively represented by hybridization
process 122 in FIG. 1) may be used to apply one or more labeled
targets to spotted arrays on microscope slides. In a particular
implementation, for instance, sample of a first target may be
labeled with a first dye (an example of what may more generally be
referred to hereafter as an emission label) that fluoresces at a
particular characteristic frequency, or narrow band of frequencies,
in response to an excitation source of a particular frequency. A
second target may be labeled with a second dye that fluoresces at a
different characteristic frequency. The excitation source for the
second dye may, but need not, have a different excitation frequency
than the source that excites the first dye, e.g., the excitation
sources could be the same, or different, lasers. The target samples
may be mixed and applied to the probes of spotted arrays on
microscope slides, and conditions may be created conducive to
hybridization reactions, all in accordance with known techniques.
In accordance with other techniques, such as typically are applied
with respect to Affymetrix.RTM. GeneChip.RTM. synthesized arrays,
samples of one labeled target are applied to one array and samples
of a second labeled target are applied to a second array having the
same probes as the first array. Hybridization techniques are
applied to both arrays. For example, synthesized arrays 134 of FIG.
1 may be illustratively assumed to be two GeneChip.RTM. synthesized
arrays that have been subject to hybridization processes with
respect to two different target samples, each labeled with
different fluorescent dyes. See, e.g., U.S. Pat. No. 6,114,122,
which is hereby incorporated by reference herein in its
entirety.
Many scanner designs may be used to provide excitation signals to
excite labels on targets or probes, and to detect the emission
signals from the excited labels. In references herein to
illustrative implementations, the term excitation beam may be used
to refer to light beams generated by lasers to provide the
excitation signal. However, excitation sources other than lasers
may be used in alternative implementations. Thus, the term
excitation beam is used broadly herein. The term emission beam also
is used broadly herein. As noted, a variety of conventional
scanners detect fluorescent or other emissions from labeled target
molecules or other material associated with biological probes.
Other conventional scanners detect transmitted, reflected, or
scattered radiation from such targets. These processes are
sometimes generally and collectively referred to hereafter for
convenience simply as involving the detection of emission beams.
The signals detected from the emission beams are generally referred
to hereafter as emission signals and this term is intended to have
a broad meaning commensurate with that intended herein for the term
emission beams.
Various detection schemes are employed depending on the type of
emissions and other factors. A typical scheme employs optical and
other elements to provide an excitation beam, such as from a laser,
and to selectively collect the emission beams. Also generally
included are various light-detector systems employing photodiodes,
charge-coupled devices, photomultiplier tubes, or similar devices
to register the collected emission beams. For example, a scanning
system for use with a fluorescently labeled target is described in
U.S. Pat. No. 5,143,854, hereby incorporated by reference in its
entirety for all purposes. Other scanners or scanning systems are
described in U.S. Pat. Nos. 5,578,832, 5,631,734, 5,834,758,
5,936,324, 5,981,956, 6,025,601, 6,141,096, 6,185,030, 6,201,639,
6,218,803, and 6,252,236; in PCT Application PCT/US99/06097
(published as WO99/47964); and in U.S. Provisional Patent
Application Ser. No. 60/286,578, each of which also is hereby
incorporated by reference in its entirety for all purposes.
FIG. 4 is a simplified graphical representation of selected
components of an illustrative type of scanner 160A suitable for
scanning hybridized spotted arrays 132A and 132B disposed on slide
333 (i.e., in this example, spotted arrays 121A and 121B,
respectively, after hybridization process 122). These illustrative
components, which will be understood to be non-limiting and not
exhaustive, are referred to collectively for convenience as scanner
optics and detectors 400. Scanner optics and detectors 400 include
excitation sources 420A and 420B (collectively referred to as
excitation sources 420). Any number of one or more excitation
sources 420 may be used in alternative embodiments. In the present
example, sources 420 are lasers; in particular, source 420A is a
diode laser producing red laser light having a wavelength of 635
nanometers and , source 420B is a doubled YAG laser producing green
laser light having a wavelength of 532 nanometers. Further
references herein to sources 420 generally will assume for
illustrative purposes that they are lasers, but, as noted, other
types of sources, eg. , x-ray sources, may be used in other
implementations.
Sources 120A and 120B may alternate in generating their respective
excitation beams 435A and 435B between successive scans, groups of
successive scans, or between full scans of an array. Alternatively,
both of sources 120 may be operational at the same time. For
clarity, excitation beams 435A and 435B are shown as distinct from
each other in FIG. 4. However, in practice, turning mirror 424
and/or other optical elements (not shown) typically are adjusted to
provide that these beams follow the same path.
Scanner optics and detectors 400 also includes excitation filters
425A and 425B that optically filter beams from excitation sources
420A and 420B, respectively. The filtered excitation beams from
sources 420A and 420B may be combined in accordance with any of a
variety of known techniques. For example, one or more mirrors, such
as turning mirror 424, may be used to direct filtered beam from
source 420A through beam combiner 430. The filtered beam from
source 420B is directed at an angle incident upon beam combiner 430
such that the beams combine in accordance with optical properties
techniques well known to those of ordinary skill in the relevant
art. Most of combined excitation beams 435 are reflected by
dichroic mirror 436 and thence directed to periscope mirror 438 of
the illustrative example. However, dichroic mirror 436 has
characteristics selected so that portions of beams 435A and 435B,
referred to respectively as partial excitation beams 437A and 437B
and collectively as beams 437, pass through it so that they may be
detected by excitation detector 410, thereby producing excitation
signal 494.
In the illustrated example, excitation beams 435 are directed via
periscope mirror 438 and arm end turning mirror 442 to an objective
lens 445. As shown in FIGS. 5A and 5B, lens 445 in the illustrated
implementation is a small, light-weight lens located on the end of
an arm that is driven by a galvanometer around an axis
perpendicular to the plane represented by galvo rotation 449 shown
in FIG. 4. Objective lens 445 thus, in the present example, moves
in arcs over hybridized spotted arrays 132 disposed on slide 333.
Flourophores in hybridized probe-target pairs of arrays 132 that
have been excited by beams 435 emit emission beams 452 (beam 452A
in response to excitation beam 435A, and beam 452B in response to
excitation beam 435B) at characteristic wavelengths in accordance
with well known principles. Emission beams 452 in the illustrated
example follows the reverse path as described with respect to
excitation beams 435 until reaching dichroic mirror 436. In
accordance with well known techniques and principles, the
characteristics of mirror 436 are selected so that beams 452 (or
portions of them) pass through the mirror rather than being
reflected.
In the illustrated implementation, filter wheel 460 is provided to
filter out spectral components of emission beams 452 that are
outside of the emission band of the fluorophore, thereby providing
filtered beams 454. The emission band is determined by the
characteristic emission frequencies of those fluorophores that are
responsive to the frequencies of excitation beams 435. In
accordance with techniques well known to those of ordinary skill in
the relevant arts, including that of confocal microscopy, filtered
beams 454 may be focused by various optical elements such as lens
465 and also passed through illustrative pinhole 467 or other
element to limit the depth of field, and thence impinges upon
emission detector 415.
Emission detector 415 may be a silicon detector for providing an
electrical signal representative of detected light, or it may be a
photodiode, a charge-coupled device, a photomultiplier tube, or any
other detection device that is now available or that may be
developed in the future for providing a signal indicative of
detected light. For convenience of illustration, detector 415 will
hereafter be assumed to be a photomultiplier tube (PMT). Detector
415 thus generates emission signal 492 that represents numbers of
photons detected from filtered emission beam 454.
FIG. 5A is a perspective view of a simplified representation of the
scanning arm portion of scanner optics and detectors 400. Arm 500
moves in arcs around axis 510, which is perpendicular to the plane
of galvo rotation 449. A position transducer 515 is associated with
galvanometer 515 that, in the illustrated implementation, moves arm
500 in bi-directional arcs. Transducer 515, in accordance with any
of a variety of known techniques, provides an electrical signal
indicative of the radial position of arm 500. Certain non-limiting
implementations of position transducers for galvanometer-driven
scanners are described in U.S. Pat. No. 6,218,803, which is hereby
incorporated by reference in its entirety for all purposes. The
signal from transducer 515 is provided in the illustrated
implementation to user computer 100B so that clock pulses may be
provided for digital sampling of emission signal 492 when arm 500
is in certain positions along its scanning arc.
Arm 500 is shown in alternative positions 500' and 500'' as it
moves back and forth in scanning arcs about axis 510. Excitation
beams 435 pass through objective lens 445 on the end of arm 500 and
excite fluorophore labels on targets hybridized to certain of
probes 370 in arrays 132 disposed on slide 333, as described above.
The arcuate path of excitation beams 435 is schematically shown for
illustrative purposes as path 550. Emission beams 452 pass up
through objective lens 445 as noted above. Slide 333 of this
example is disposed on translation stage 542 that is moved in what
is referred to herein as the y direction 544 so that arcuate path
550 repeatedly crosses the plane of arrays 132.
FIG. 5B is a top planar view of arm 500 with objective lens 445
scanning arrays 132 as translation stage 542 is moved under path
550. As shown in FIG. 5B, arcuate path 550 of this example is such
that arm 500 has a radial displacement of .theta. in each direction
from an axis parallel to direction 544. What is referred to herein
as the x direction, perpendicular to y-direction 544, is shown in
FIG. 5B as direction 543. Further details of confocal,
galvanometer-driven, arcuate, laser scanning instruments suitable
for detecting fluorescent emissions are provided in PCT Application
PCT/US99/06097 (published as WO99/47964) and in U.S. Pat. Nos.
6,185,030 and 6,201,639, all of which have been incorporated by
reference above. It will be understood that although a
galvanometer-driven, arcuate, scanner is described in this
illustrative implementation, many other designs are possible, such
as the voice-coil-driven scanner described in U.S. patent
application Ser. No. 09/383,986, hereby incorporated herein by
reference in its entirety for all purposes.
FIG. 6A is a simplified graphical representation of illustrative
probe 370A as it is scanned by scanner 160A. It is assumed for
illustrative purposes that probe 370A has hybridized with a
fluorescently labeled target. Although FIG. 6A shows probe 370A in
idealized form, i.e. a perfect circle, it will be understood that
many shapes, including irregular shapes, are possible.
In the manner described above, objective lens 445 scans over probe
370A (and other probes of arrays 132) in bi-directional arcs. An
illustrative scan 620 is shown in FIG. 6A, which is not necessarily
drawn to scale; e.g., the ratio of the radius of the arc of scan
620 to the radius of probe 370A is illustrative only. As also
noted, probe 370A moves under objective lens 445 carried by
translation stage 542 in y-direction 544. In particular, in the
illustrated implementation, arm 500 scans in an arc in one
direction, shown as left-to-right scan 620 in FIG. 6A. Translation
stage 542 is then moved incrementally by a stepping motor (not
shown) in y-direction 544 and arm 500 then scans back in the
opposite direction, shown as right-to-left arcuate scan 622.
Translation stage 542 is again moved in direction 544, and so on in
scan-step-scan-step sequences. The distance between scans 620 and
622 thus corresponds to the distance that translation stage 542 is
moved in each increment, although it will be understood that the
distance shown in FIG. 6A is not necessarily to scale and is
illustrative only. It will be understood that any other combination
of scanning and stepping is possible in alternative
implementations, and that scanning and moving of translation stage
542 may occur at the same or at overlapping times in some
implementations. Translation stage 542 need not be stepped in some
implementations, but may, for example, be moved continuously.
FIG. 6B is a plot having a pixel clock axis 630 showing when clock
pulses 632 occur. Clock pulses 632 may be generated by a pixel
clock of scanner 160A (e.g., complex programmable logic device 830,
described below) or, alternatively, they may be generated by
software executing in computer 100B (e.g., executable 790',
described below). Axis 630 in the illustrated implementation is a
spatial axis; that is, each of clock pulses 632 occurs in reference
to the radial location of arm 500 during each scan, as described in
greater detail below. Thus, with reference to the position of
translation stage 542 indicated by scan 620, a clock pulse 632A
occurs prior to arm 500 passing over probe 370A from the left as
shown in FIGS. 6A and 6B. (For sake of clarity of illustration
only, vertical dotted lines are provided between FIGS. 6A and 6B,
and between FIGS. 6B and 6C, to illustrate the alignment of these
figures.) As another example, clock pulse 632C occurs with respect
to scan 620 when arm 500 has just passed over portions of probe
370A indicated by pixel areas 610A and 610B. These areas are
referred to as pixel areas because a digital value is assigned to
each such area in the illustrated implementation based on the
strength of a processed emission signal associated with that area.
In accordance with known techniques, clock pulses 632 enable the
digital sampling of the processed emission signal.
As noted, clock pulses 632 are spatially rather than temporally
determined in the illustrated implementation. Moreover, in some
aspects of the illustrated implementation, galvanometer 516 is
driven by a control signal provided by user computer 100B such that
the velocity of arm 500 in x-direction 444 is constant in time
during those times when arm 500 is over probe 370A (and, typically,
over other of probes 370 of arrays 132 as they are scanned). That
is, dx/dt is a constant (and thus the angular velocity varies) over
the probe-scanning portions of each arc and, in particular, it is a
constant during the times when clock pulses are generated to enable
digital sampling. As is evident, dx/dt must be reduced to zero
between each successive scan, but this deceleration and reversal of
direction takes place after arm 500 has passed over probe 370A (or,
more generally, array 132A or 132B). The design and implementation
of a galvanometer control signal to provide constant dx/dt are
readily accomplished by those of ordinary skill in the relevant
art.
Thus, the approximate sampling rate may readily be calculated based
on the desired scanning speed (dx/dt) and desired pixel resolution.
To provide an illustrative example, a spot deposited by an
Affymetrix.RTM. 417.TM. or 427.TM. Arrayer typically has a diameter
of approximately 150 to 200 microns. Spotted arrays made using
these instruments typically may be deposited over a surface having
a width of about 22 millimeters on a microscope slide that is 25
millimeters wide. In order to achieve pixel resolution of about 10
microns, a sampling rate of about 160 kHz is sufficient for
scanning speeds typical for scanners used with respect to these
probe arrays, such as the Affymetrix.RTM. 428.TM. scanner. Other
sampling rates, readily determined by those of ordinary skill, may
be used in other applications in which, for example, different
scanning speeds are used and/or different pixel resolutions are
desired. The desired pixel resolution typically is a function of
the size of the probe features, the possibility of variation in
detected fluorescence within a probe feature, and other
factors.
FIG. 6C shows digital values representative of emission signal 492
as sampled at (and/or collected for an adjoining period before)
points on scans 620 and 622 represented by constant radial position
lines 625A-K (collectively referred to as radial position lines
625). The voltages sampled during scan 620 are shown as dots, while
the voltages sampled during scan 622 are shown as x''s. The
determination of when to initiate pixel clock signals may be made
using position transducer 515, as described in greater detail in
U.S. Provisional Patent Application Ser. No. 60/286,578,
incorporated by reference above. Thus, for example, voltage 650C of
FIG. 6C is representative of emission signal 492 based on sampling
enabled by a pixel clock pulse at point 632C on axis 630 that is
triggered when arm 500 is at radial position 625C during scan 620.
After translation stage 542 has been incremented, voltage 652C is
sampled during scan 622 at the same radial position, shown as
radial position 625C''.
User Computer 100B
As shown in FIG. 1 and noted above, scanner 160B operates in the
illustrated implementation under computer control, e.g., under the
control of user computer 100B, as shown in greater detail in FIG.
7. Although computer 100B is shown in FIGS. 1 and 7 for clarity as
being directly coupled to scanner 160A, it may alternatively be
coupled to scanner 160A over a local-area, wide-area, or other
network, including an intranet and/or the Internet. Computer 100B
may be a personal computer, a workstation, a server, or any other
type of computing platform now available or that may be developed
in the future. Typically, computer 100B includes known components
such as processor (e.g., CPU) 705, operating system 710, system
memory 720, memory storage devices 725, GUI controller 715, and
input-output controllers 730, all of which typically communicate in
accordance with known techniques such as via system bus 704. It
will be understood by those skilled in the relevant art that there
are many possible configurations of the components of computer 100B
and that some components that may typically be included in computer
100B are not shown, such as cache memory, a data backup unit, and
many other devices.
Input-output controllers 730 could include any of a variety of
known devices for accepting and processing information from a user,
whether a human or a machine, whether local or remote. Such devices
include, for example, modem cards, network interface cards, sound
cards, or other types of controllers for any of a variety of known
input devices. Output controllers of input-output controllers 730
could include controllers for any of a variety of known display
devices for presenting information to a user, whether a human or a
machine, whether local or remote. If one of these display devices
provides visual information, this information typically may be
logically and/or physically organized as an array of picture
elements, sometimes referred to as pixels. Graphical user interface
(GUI) controller 715 may comprise any of a variety of known or
future software programs for providing graphical input and output
interfaces between computer 100B and a user 701 (e.g. , an
experimenter wishing to use scanner 160A to acquire and analyze
information from spotted arrays), and for processing inputs from
user 701 (hereafter sometimes referred to as user inputs or user
selections). To avoid confusion, references hereafter to a GUI
generally are directed to one or more graphical user interfaces
displayed on a display device of devices 780 to user 701, such as
GUI 782A of FIGS. 8 and 9, described below. To be distinguished are
references to a GUI controller, such as GUI controller 715, that
operates to display the GUI''s to user 701 and to process input
information provided by user 701 through the GUI''s. As is well
known in the relevant art, a user may provide input information
using a GUI by selecting, pointing, typing, speaking, and/or
otherwise operating, or providing information into, one or more
input devices of devices 780 in a known manner.
Computer 100B may optionally include process controller 740 that
may, for example, be any of a variety of PC-based digital signal
processing (DSP) controller boards, such as the M44 DSP Board made
by Innovative Integration of Simi Valley, Calif. More generally,
controller 740 may be implemented in software, hardware or
firmware, or any combination thereof.
Scanner control and analysis application 790 of the illustrated
implementation is a software application that controls functions of
scanner 160A. In addition, when executed in coordination with
processor 705, operating system 710, GUI controller 715, and/or
process controller 740, application 790 performs user interface
functions, data and image processing operations, and data transfer
and storage operations related to data provided by or to scanner
160A and/or user 701, as described in greater detail below.
Affymetrix.RTM. Jaguar.TM. software, available from Affymetrix,
Inc., is a commercial product that, in some implementations,
includes various aspects of application 790.
As will be evident to those skilled in the relevant art,
application 790 may be loaded into system memory 720 and/or memory
storage device 725 through an input device of devices 780.
Alternatively, application 790 may be implemented as executable
instructions stored in firmware, or a combination of firmware and
software. Executable code corresponding to application 790 is
referred to as scanner control and analysis application executable
790' and is shown for convenience with respect to the illustrated
implementation as stored in system memory 720. However,
instructions and data including executable instructions of
executable 790', and data used or generated by it, may be located
in or shifted among other memory devices, local or remote, as
convenient for data storage, data retrieval, and/or execution. The
instructions of executable 790', also called computer control
logic, when executed by processor 705, enable computer 100B to
perform functions of the illustrated systems. Accordingly,
executable 790' may be referred to as a controller of computer
100B. More specifically, in some implementations, the present
invention includes a computer program product comprising a computer
usable medium having control logic (computer software program,
including program code) stored therein. In various embodiments,
software products may be implemented using any of a variety of
programming languages, such as Visual C++ or Visual Basic from
Microsoft Corporation, Java.TM. from Sun Microsystems, Inc., and/or
other high or lower level programming languages. The control logic,
when executed by processor 705, causes processor 705 to perform
some of the functions of the invention, as described herein. In
other embodiments, some functions of the present invention may be
implemented primarily in hardware using, for example, a hardware
state machine. Implementation of the hardware state machine so as
to perform the functions described herein will be apparent to those
skilled in the relevant arts.
Gain Adjustment Components 890
FIG. 8 is a simplified functional block diagram of one example of a
configuration of gain adjustment components of illustrative scanner
system 150A. For convenience of illustration, these components are
described with reference to user computer 100B of FIGS. 1 and 7 and
scanner 160B of FIGS. 1, 4, 5A, and 5B, although it will be
understood that many alternative computer and/or scanner
implementations are possible. For sake of clarity, FIG. 8 omits
some aspects of computer 100B and scanner 160B as described above
(e.g., communications among components of computer 100B via system
bus 704), the functions of which are implicit in FIG. 8 and will be
evident to those of ordinary skill in the relevant art.
A reason for providing gain adjustment is that, under certain
conditions, the dynamic range of scanner 160B may be exceeded. For
example, the dynamic range of scanner 160B may be exceeded due to
excitation source 420A or 420B having been set at too high a gain,
a higher-than-anticipated responsiveness of labels to excitation
beams 435, a high gain setting of emission detector 415, a high
gain setting of circuitry that amplifies emission signal 492 (e.g.,
variable gain amplifier 815, described below), or for other
reasons. When the dynamic range is exceeded, some image pixels
displayed to represent emission signal intensities may appear to be
equally bright even though they represent emissions of varying
intensities. This effect, whatever its cause, may interfere with
the implementation of conventional techniques that, for example,
search for the boundaries between bright and dim elements in an
alignment pattern. The unintended result may be that an alignment
grid is inaccurately positioned over an image because the grid was
inaccurately aligned with an alignment pattern defined by
boundaries between bright and dim pixels. See, e.g., U.S. patent
application Ser. No. 09/681,819, hereby incorporated herein in its
entirety for all purposes. Another unintended result may be that
data regarding emission signal values is lost due to signal
saturation.
One example of a saturation effect is illustrated by FIGS. 6C and
6D. In FIG. 6C, analog voltage values of emission signal 492 (or
amplified and/or filtered versions of that signal, as described
below) are sampled by process controller 740 according to pixel
clock pulses 632. The sampled analog voltages are shown on axis 640
of FIG. 6C, some of which (such as voltages 650I and 650H) are
above a saturation value 660. Saturation value 660 typically is
imposed because of limitations in digital conversion such as
represented by digital conversion range 662. For example, it may be
determined, based on desired resolution, anticipated dynamic range,
and digital processing constraints, that analog voltages within
range 662 will be converted to digital values between 0 and
2.sup.16 -1, i.e., between 0 and 65,535. Analog voltages above
value 660 would thus typically be represented by digital values
690H and 690I at the maximum digital conversion value represented
by maximum digital voltage line 672. Specifically, in this example,
the digital value both of values 690H and 690I is 65,535, even
though corresponding analog voltages 650I and 650H have different
values. It is also possible that hardware limitations, such as the
range of power supplies in amplifier 815, described below, impose
an analog saturation voltage such that voltages 650I and 650H would
have a same value even though they represented emissions of
different intensities. Similarly, emission detector 415 may
saturate so that values of emission signal 492 are constant above a
saturation value.
The gain adjustment components of scanner 160A, as shown in the
illustrated implementation of FIG. 8, include emission detector
415, filters 810 and 820, variable gain amplifier 815, and CPLD
830. Emission detector 415 may be any of a variety of conventional
devices including, for example, a photomultiplier tube (PMT), such
as included in the HC 120 Series PhotoSensor Modules available from
Hamamatsu Corporation USA of Bridgewater, N.J. VGA 815 is a type of
what more generally is referred to as a variable gain element. VGA
815 may be any of a variety of conventional amplification devices
such as the model AD603 amplifier available from Analog Devices of
Norwood, Mass. CPLD 830 may be any conventional CPLD (or similar
device such as a Field Programmable Gate Array), such as are
available from Altera Corporation of San Jose, Calif., or other
suppliers.
Filter 810 may be any filter designed to eliminate high frequency
spikes that may be present in signal 492 and thus provide
protection to VGA 815. As described in U.S. Provisional Patent
Application Ser. No. 60/286,578 incorporated above, it generally is
desirable for bidirectional scanning, such as in the illustrated
implementation of FIGS. 4, 5A, 5B, and 6A, that the rise and fall
response characteristics of emission signal filters be symmetrical.
Thus, linear-phase filters, such as high-order Bessel filters, may
advantageously be employed. In particular, filter 810 may be the
first stage of a Bessel filter. Filter 820 may advantageously
comprise additional Bessel filter stages having the desired
response characteristics while providing low-pass filtering of
noise in emission signal 492. As described in application
60/286,578, noise may be present due to the use of relatively
inexpensive lasers such that noise in excitation beams 435 causes
corresponding noise in emission beams 452.
CPLD 830 provides pixel clock pulses 632 to controller 740 so that,
in accordance with known analog-to-digital techniques, it may
sample analog emission signal 822. CPLD 830 determines clock pulses
632 in the illustrated implementation by comparing radial position
information from galvo position transducer 515 with radial position
data stored in system memory 220, as described in application
60/286,578.
User-Selected Gain Adjustment: The illustrative configuration of
components of scanner system 150A shown in FIG. 8, and GUI 782A
shown in FIG. 9, address the problem of emission signal saturation
based either on user-selected gain adjustment or automatic gain
adjustment. Illustrative implementations are now described with
respect to FIGS. 10, 11, 12A, and 12B that are directed to the
option of user-selected gain adjustment.
In this illustrative implementation, GUI 782A is employed to enable
user 701 to vary emission detector control signal 784 over a first
range of values and/or to vary variable gain element (VGA) control
signal 783 over a second range of values, thereby controlling the
gains of emission detector 415 and variable gain amplifier 815,
respectively, during the scanning process (also referred to herein
as a scanning operation). User 701 may determine that a gain
adjustment is desirable by inspecting an image comprising scanned
pixels, generated as described above with respect to FIGS. 6A-6D,
for a previously conducted experiment similar to a new experiment,
or a prior attempt at conducting the first experiment. User 701 may
note that a significant portion of the previously scanned pixels in
the prior experiment or prior attempt were uniformly and maximally
bright (perhaps indicating saturation due to excessive scanner
gain), that there are no maximally bright pixels (perhaps
indicating that a low gain setting has resulted in a
less-than-attainable dynamic range), or that there are a
significant number of dark pixels (again perhaps indicating
less-than-attainable dynamic range). Alternatively, during the
previously conducted scan, executable 790' may have counted the
number of pixels having digital voltage values represented by
maximum digital voltage line 672. If this number exceeded either a
predetermined or user-selected threshold, executable 790' could
have provided an appropriate message to user 701 through a
graphical user interface or another conventional technique.
Similarly, executable 790' may have counted the number of dark
pixels to determine, for example, if the proportion of dark pixels
exceeds an anticipated threshold. In any of these cases, user 701
may decrease the gain to avoid saturation or increase the gain to
improve resolution of small signals for future scanning operations.
These, and other, optional operations by executable 790' are
described below in relation to implementations including automatic
gain adjustment.
More generally, user 701 may determine the desired gain based on a
variety of additional factors, such as experience with scanner
160A, experience with the fluorescent labels in particular dyes to
be used, and so on. By rescanning multiple times at a series of
gain settings, user 701 may obtain measures of pixel intensities
across a range that exceeds the dynamic range of the scanner. For
one example of how extended dynamic range may be determined, see
U.S. Pat. No. 6,171,793, hereby incorporated by reference herein
for all purposes.
FIG. 9 is a graphical representation of one of many possible
implementations of GUI 782A. GUI 782A includes up-arrow and
down-arrow graphical elements 912 and 914 that, in accordance with
known techniques, enable user 701 to respectively increase or
decrease a value displayed in graphical element 910. For example,
user 701 may illustratively be assumed to be enabled to vary the
value displayed in element 916 between 0 and 70, wherein the
selected value represents a decibel (dB) value within this range.
In this manner, user 701 may set a gain in relation to a reference
gain at which scanner 160A nominally operates, i.e., operates when
the user-selected gain value is zero.
The reference gain in this example is illustratively assumed to be
set by the maker of scanner 160A in accordance with various
objectives. One objective may be to ensure that the reference gain
is sufficiently low that saturation will not occur at that level.
Thus, user 701 may be presented simply with the option of
increasing gain in order to more accurately identify low-intensity
emissions and need not be concerned with saturation if the
user-selected gain value remains at zero. In alternative
implementations, the reference gain may be set higher and the user
provided with options for decreasing, as well as increasing, the
gain of scanner 160A in relation to that reference.
Another objective that may be relevant to establishing the
reference gain is to calibrate scanner 160A with other scanners.
For example, a technician may adjust the reference gain based on
scanning a benchmark fluorescent feature on a calibration slide.
The technician measures the value of emission signal 492 when the
benchmark is excited and adjusts the gain of emission detector 415
so that signal 492 is a standard value. As noted, this standard
value is low enough to ensure that saturation will not occur if the
user-selected gain value remains at a default value of zero. This
procedure typically is repeated for each of excitation sources 420
because the response of emission detector 415 may vary depending on
the wavelength of filtered emission beam 454.
In the illustrated implementation, it is illustratively assumed
that the gain of emission detector 415 may be varied over a range
of 60 decibels by varying a control voltage (shown in FIG. 8 as
emission detector control signal 784). It is further illustratively
assumed that up to 30 decibels is reserved for making the
calibration. That is, even if the calibration requires an increase
of 30 decibels in emission signal 492, a range of an additional 30
decibels will be available for user-selected adjustment of signal
492. FIG. 10 is a graphical representation of an illustrative
distribution of both calibration and user-selected gain settings as
applied to emission detector 415 and variable gain amplifier 815.
As shown in FIG. 10, executable 790' stores the calibrated gain
settings for each of excitation sources 420 in a memory unit of
computer 100B, as illustratively represented by calibration data
798 in system memory 720 of the present example. For instance, data
798 may include records specifying that the calibration setting for
detector 415 when source 420A (e.g., diode laser) is operational is
15 decibels, and the calibration setting for detector 415 when
source 420B (e.g., doubled YAG laser) is operational is 5 decibels.
These functions are indicated in FIG. 10 by the dotted line showing
the correspondence between calibration range 1040 (30 dB in this
example) and executable 790', and the transfer of the calibration
control value from data 798 via executable 790' and emission
detector control signal 784 to emission detector 415.
In a specific illustrative implementation, a gain value, as
selected by user 701 using graphical elements 912 or 914 and
displayed in element 910, is provided to executable 790' in
accordance with known GUI techniques. User 701 typically may wish
to select a gain value that is specific to the particular one of
excitation sources 420 used to generate emission signal 492. This
option is desirable because, as noted, the response of emission
detector 415 may vary depending on the wavelength of emission
signal 492 that, in turn, generally depends on the wavelength of
the excitation signal generated by the excitation source. Other
experimental parameters, such as the type of label (e.g.,
fluorophore dye), may similarly influence user 701''s selection of
gain. In the example shown in FIG. 9, user 701 has determined that
for a scanning operation related to a particular experiment
identified in graphical element 910, in which the dye CY5 (see
graphical element 927) may have been associated with hybridized
probe-target pairs of one of arrays 132, and in which the array is
to be excited by red diode laser 420A (see graphical element 925),
the user-selected gain should be 43 decibels (see graphical element
916). User 701 could similarly specify that, in the same scanning
operation, another dye is also potentially present and that another
one of sources 420 is to be used (in the same or sequential scan,
depending on the design of scanner 160A) to excite the fluorophores
of this dye, if present.
It is now illustratively assumed that user 701 instructs executable
790' to cause scanner 160A to scan an array in a scanning operation
undertaken in accordance with the experiment represented in FIG. 9.
Executable 790' causes digital signals to be generated that
represents the user-selected gain values for the specified
excitation sources, and these signals are provided to a
digital-to-analog converter (not shown) that provides analog
control signals representative of the user-selected gain values,
all in accordance with any of a variety of known techniques. For a
gain value between zero and 40 decibels in the illustrated
implementation, executable 790' causes switching to be enabled such
that the representative analog value (e.g., VGA control signal 783)
is provided to a control input of variable gain element (VGA) 815.
Thus, for instance, user 701 may select a gain of 5 decibels by
manipulating elements 912 or 914 as described above or, in an
alternative implementation of aspects of GUI 782A shown in FIG. 10,
placing user-selectable slide element 1005 to a first position A as
represented by element 1005A. The result in either case is that a
control voltage is applied to VGA 815 such that, in accordance with
known techniques, amplified analog emission signal 817 is increased
by 5 decibels over a nominal operating gain (e.g., unity) for VGA
815. In this illustrative range of zero to 40 decibels, no portion
of the user-selected gain is allocated to emission detector 415;
i.e., all of the user-selected gain is allocated to VGA 815. Thus,
the portion of user-selected gain allocated to emission detector
415 may hereafter be referred to as a no-change value to indicate
that, although the gain of emission detector 415 may have been
adjusted for purposes of calibration or for other reasons, it is
not adjusted based on the user-selected gain in this example.
For user-selected gain values of 40 decibels and above in the
illustrated implementation, executable 790' maintains emission
detector control signal 784 such that the output of VGA 815, i.e.,
emission signal 817, is increased by 40 decibels above its nominal
0 dB level. Executable 790' also causes emission detector control
signal 784 to assume a value representative of the amount that the
user-selected value exceeds 40 decibels. For instance, if user 701
selects 45 dB, as represented by user-selectable slide element
1005B, VGA control signal 783 is set at a value such that VGA 815
provides 40 decibels of gain, and emission detector control signal
784 assumes a value such that emission detector 415 provides an
additional 5 decibels of gain.
It will be understood that many other techniques are available by
which user 701 may select a desired gain and by which a portion of
this gain may be implemented by emission detector 415 and a portion
by variable gain amplifier 815. For example, the initial range of
gain could be implemented by emission detector 415 rather than by
VGA 815 as in the illustrated example. Also, any user-selected gain
could be implemented in a same range in any proportion between
emission detector 415 and VGA 815. For example, any gain selected
by user 701 could be implemented 50% by emission detector 415 and
50% by VGA 815. Further, in some implementations, any available
capacity in calibration range 1040 (e.g., if scanner 160A were
calibrated at 20 decibels so that 10 decibels of the 30 decibels in
range 1040 were available) could be provided for user-selected gain
so that, in the illustrated example, user-selectable range of gain
values 1020 could be increased from 30 decibels to 40 decibels.
Also, many alternative user interfaces may be used. For example,
GUI gain adjustment element 1000 was described above as having a
single user selectable slide element 1005 that could be moved by
user 701 between various positions such as positions A and B of the
illustrated example. In one of many alternative implementations,
two slide elements could be provided so that user 701 could
separately select a gain attributed specifically to emission
detector 784 (e.g., a separate slide element 1005B operating over a
range of gain values 1020) and a gain attributed specifically to
VGA 815 (e.g., a separate slide element 1005A operating over a
separate range of gain values 1030). In this alternative
implementation, gain ranges 1020 and 1030 could, of course, be
separated from each other rather than stacked.
FIG. 11 is a functional block diagram including elements of
application executable 790' that implement some of the operations
described above with respect to the illustrative example. FIGS.
12A-C are flow charts showing method steps corresponding to some of
these operations. As shown in FIG. 11, application executable 790'
includes calibration-gain data manager 1110 that receives
calibration-gain data (i.e., values of calibrated gains for each of
excitation sources 420) input by technician 1101 through an
appropriate user interface (not shown). (See corresponding method
step 1205.) Calibration-gain data manager 1110 stores this data in
appropriate records or other data-storage formats of calibration
data 798 so that a calibration gain is associated with each of
excitation sources 420 (see step 1210).
Application executable 790' also includes user-selected gain data
manager 1120 that receives the user-selected gain to be applied to
emission detector 415 and VGA 815. This gain may input via GUI 782A
of FIG. 8, or alternative interfaces such as that employing
graphical elements 912 and 914 or user-selectable slide element
1005. The user-selected gain typically is associated by user 701
with particular ones of excitation sources 420 and/or particular
experiments in which, for example, certain dyes with fluorescent
labels are to be used. (See corresponding method step 1225.) Thus,
user 701 may repeatedly use GUI 782A, or another interface, to
select a gain to be used for particular excitation sources and/or
experiments. User-selected gain data manager 1120 stores this data
in appropriate records or other data-storage formats of scanner
gain data 799 so that a user-selected gain is associated with each
of excitation sources 420, typically for each of one or more
specified experiments (see step 1230).
For example, an illustrative record 799A is shown that stores the
information that, when a particular scan of a microarray
experiment, identified as Scan ID=0001, is performed, emission
signal 492 from red diode laser source 420A is to be amplified by
45 decibels by providing a gain of 5 decibels from emission
detector 415 and 40 decibels from VGA 815. It is illustratively
assumed that user 701 directs scanner 160A to perform scan 0001 by
using an interface such as illustrative GUI 782A that is
graphically represented in FIG. 9 (see step 1260 and graphical
elements 940 or 950, described below).
Application executable 790' includes scan gain controller 1130
that, in accordance with any of a variety of known data search and
retrieval techniques, retrieves record 799A. Alternatively, rather
than storing scanner gain data 799 and later initiating a scan,
user 701 may specify scanner gain data 799 and provide scan
initiation data 1106 using a common user interface and/or in a
common operation in accordance with other known techniques. (See
step 1270.) Scan initiation data 1106 typically includes an
indicator that user 701 has initiated a scan or a preview scan,
such as may be done, for example, by selecting graphical elements
950 or 940, respectively. Also, initiation data 1106 may include
other information such as a selected preview resolution, described
below.
Based on scanner gain data 799, scan gain manager 1130 allocates
the user-selected gain value between emission detector 415 and VGA
815 (see step 1275). Scan gain manager 1130 then applies these
gains by, for example, causing emission detector control signal 784
to be sent to emission detector 415 to set its gain at 5 decibels
and causing VGA control signal 783 to be sent to VGA 815 to set its
gain at 40 decibels (see step 1280). Typically, these control
signals are provided via a conventional output device of
input/output devices 780 (see step 1280).
Automatic Gain Adjustment: User 701 also may choose to employ
automatic gain adjustment rather than user-selected gain adjustment
as just described. This choice may be implemented in accordance
with a variety of known techniques, such as by user 701 selecting
graphical element 920. Typically, this selection deactivates
graphical elements for the implementation of user-selected gain
(e.g., by graying out element 916 and deactivating elements 912 and
914). However, in some implementations, both options may be
provided so that, for example, a user-selected gain value is used
if the automatic gain adjustment technique is not able to function
due to a lack of data or other reason. Also, automatic gain
adjustment may be a default option, or it may be provided without
providing the option of user-selected gain adjustment.
FIG. 13 is a flow chart showing steps by which, in one illustrative
embodiment, scan gain controller 1130 automatically determines a
gain, allocates it between emission detector 415 and VGA 815, and
applies it to those elements.
As indicated by method step 1305, controller 1130 in this example
determines whether user 701 has enabled the automatic gain feature.
If user 701 has not enabled the automatic gain feature, or it is
de-selected by default or otherwise not enabled, a user-selected
gain may be determined and allocated as described above (see step
1307, invoking step 1250).
If user 701 has enabled the automatic gain feature, user 701 in
this example may also optionally provide parameters according to
which a preview scan will be initiated by controller 1130 (see step
1315). Controller 1130 causes a preview scan to be made in order to
obtain pixel intensity samples indicative of the range of pixel
intensities in the scanned image (see step 1320).
To provide one of many possible examples of the implementation of
steps 1315 and 1320, it is illustratively assumed that user 701
selects graphical element 942 (labeled Preview Resolution) to be 20
microns, as shown in GUI 782A of FIG. 9. Assuming, as above, a
nominal pixel resolution of 10 microns, then this user selection is
illustratively assumed to indicate that each group of two pixel
values is averaged to provide a single sample pixel value. Thus,
this user selection specifies a resolution parameter such that the
resolution is 20 microns, or half the nominal resolution value. In
alternative implementations, this user selection could indicate
that only every other pixel is obtained or recorded, thus providing
another sample measure for the same resolution.
It further is illustratively assumed in accordance with previous
examples that translation stage 542 moves 10 microns in the y
direction between each line scan. The user selection in this
example of 20 micron pixel resolution may further be implemented by
scanning every other line rather than every line, thus reducing the
pixel resolution in the y direction also by half. Thus, for
instance, in a regular scan mode, sample pixels are obtained both
for scans 620 and successive scan 622 of the example of FIG. 6A.
When user 701 selects 20 microns for the value of graphical element
942 indicating one half the nominal resolution, then, in this
specific implementation, pixels from every other scan line, rather
than every scan line, are included in the samples. Similarly, user
701 may select 50 micron resolution, resulting in this illustrative
implementation in the averaging of every five 10-micron pixels in
each scan line, and scanning only one-fifth as many lines in the y
direction as would nominally be the case. That is, translation
stage 542 is stepped five increments between scans, rather than the
nominal one increment. As can be seen from FIG. 6A, at least two
scan lines of sample pixels would be obtained from scanning probe
370A even if user 701 had elected to obtain sample pixels only from
every fifth scan line, assuming that probe 370A is a spot of about
150 to 200 microns diameter, as is typical in some
applications.
It will be understood that scanner 160A typically scans across many
probes in each scan line. The scan line may extend from one edge of
the substrate (e.g., microscope slide) to the other, or at least
across the width of a portion of the substrate often referred to as
a scanning area because within it are contained the features (i.e.,
in the present example, probes or probe-target pairs, sometimes
therefore referred to as probe features) to be scanned. The
locations on the substrate where probe features are located may
therefore be referred to herein as probe-feature locations.
Similarly, translation stage 542 typically is moved a sufficient
distance in the y direction so that the full height of the scanning
area is scanned. In the illustrated example of GUI 782A of FIG. 9,
user 701 may define the scanning area by selecting values in a
graphical portion 960 (labeled Scan Area). For example, a value for
X in portion 960 indicates a distance in the x direction from the
left edge of the slide to the left edge of the scanning area, a
value for Y in portion 960 indicates a distance in the y direction
down from the top edge of the slide to the top edge of the
illustrative rectangular scanning area, and the Width and Height
values in portion 960 specify the width and height of the
illustratively rectangular scanning area. Alternatively, user 701
may employ conventional drag or other techniques to change the
dimensions of the scanning area as represented by the rectangular
graphical element 970 of this example. It will be understood that
the scanning area need not be a rectangle in other implementations,
but may be any shape.
Controller 1130 may store the sample pixel intensity values
collected during the preview scan over the scanning area in an
appropriate data structure, such as represented by sample intensity
data 797 stored in system memory 720 as shown in FIG. 7. Based on
these sample values, controller 1130 determines a value for the
automatic gain adjustment (see step 1330). This determination may
be made in a variety of ways. One illustrative technique is
represented by the flow chart of FIG. 14 and the functional block
diagram of FIG. 15. As shown in step 1410, controller 1130
determines an initial auto-gain value for a first iteration of the
preview scan (see auto-gain value selector 1505). For instance,
using the present example of a 70 decibel range of gain achieved by
a combination of gain from emission detector 815 and gain from VGA
415, controller 1130 may select an initial gain at the mid-point of
this range, i.e., 35 decibels, although any other initial value may
be selected in other implementations. Controller 1130 may, but need
not, allocate this 35 decibels of gain between emission detector
815 and VGA 415 in the same manner as described above with respect
to the allocation of user-selected gain. Thus, in the illustrated
example in which the first 40 decibels is allocated to VGA 415
(above the calibration gain allocated to emission detector 815),
the 35 decibels would all be allocated to VGA 415. As indicated by
step 1420 and described above, sample pixels are then collected for
the scanning area at the user-selected resolution and with the
initial value of auto gain selected by controller 1130 (see
intensity manager 1540).
Controller 1130 then compares the distribution of sample pixel
intensities to a desired distribution (see comparison manager
1550). This comparison may be accomplished in accordance with any
of a wide variety of statistical and other techniques. In some
applications, a statistical measure, such as a mean or average, may
be calculated and compared with a desired mean or average
intensity. Generally, however, such an approach would not
necessarily take into account the characteristics of a typical scan
in which, for example, the number of background pixels, i.e.,
pixels associated with a dark background (i.e., no fluorescent
probe-target features possible since probes were not deposited) are
relatively large and relatively predictable. Thus, it typically is
advantageous to devise a comparison technique that takes into
account expected relationships of low intensity (hereafter
sometimes referred to for convenience as dark) pixels to high
intensity (light) pixels, including the expected relationship of
background pixels to probe pixels, i.e. pixels associated with
probes that may be associated with fluorescent labels or other
emission labels.
As but one non-limiting example of a technique that accounts for
anticipated scan characteristics, controller 1130 may assign each
pixel intensity value to a bin of a histogram. As in the example of
digital conversion range 662 of FIG. 6C, the possible digital range
of these pixel intensity values in this illustration is between 0
and 65,535. Thus, for instance, 15 bins may be used wherein bins 1
through 5 contain the lower intensity values (where pixels of
intensity value 0 are assigned to bin 1), bins 6 through 10 contain
mid-range intensity values, and bins 11 through 15 contain
high-range intensity values (where pixels of intensity value 65,535
are assigned to bin 15).
Controller 1130 calculates in this specific illustrative example a
ratio determined by dividing the number of pixel intensity values
in the mid-range bins by the number of pixel intensity values in
the high-range bins. If this ratio is equal to or greater than 2.0,
then the auto-gain used to conduct the preview scan is deemed to be
satisfactory. This determination, as indicated, may be based on
empirical data from successful scans under various conditions of
dyes, excitation sources, and other factors; on knowledge of
expected ratios of background pixels to probe pixels; on knowledge
of expected intensity ranges of fluorescent signals; and/or other
considerations. Various other tests or comparisons may be applied.
For example, if the number of intensity values in bin 15 is above
some threshold expected value, then it may be concluded that
saturation has occurred and that the auto gain used in the preview
scan was too high. Similarly, a high number of intensity values in
bin 1 may indicate that the auto gain was set too low. Many
varieties and combinations of such tests and comparisons will now
be appreciated by those of ordinary skill in the relevant art based
on the present description.
If the ratio mentioned above is less than 2.0 in this specific
example, controller 1130 concludes that the auto gain used for the
preview scan was too high, thus resulting in a greater than desired
or expected number of intensity values in the high-range bins.
Alternatively, as noted in one of many alternative or additional
tests, controller 1130 may draw the same conclusion based on the
number of intensity values in the high-range bins. In any event, it
is now illustratively assumed that controller 1130 determines that
the actual distribution of intensity values did not conform to the
expected or desired intensity value distribution because of a
surplus of light pixels (see no exit from decision element 1440).
Controller 1130 then reduces the auto gain in accordance with any
of a variety of techniques (see step 1440). For example, controller
1130 may reduce the gain by one-half, i.e., to 35 dB-6 dB=29
decibels in an illustrative specific, non-limiting, example.
Another preview scan may then be done (see step 1420) using the
revised auto gain of 29 decibels. If controller 1130 determines
that this gain also is too high, then this value may be reduced by
about one-half, i.e., to 29 dB-6 dB=23 decibels, and this new
auto-gain value used in another preview scan.
Similarly, if the ratio mentioned above exceeds the target ratio
value of about 2.0 in this specific example by a threshold amount
(e.g., if the ratio is 4.0 or above), controller 1130 may concludes
that the auto gain used for the preview scan was too low, thus
resulting in a greater than desired or expected number of intensity
values in the mid- (and/or low-) range bins. Alternatively, as
noted, controller 1130 may draw the same conclusion based on the
number of intensity values in the mid- or low-range bins. In any of
these cases, controller 1130 consequently increases the auto gain
in accordance with any of a variety of techniques (see step 1440
and auto-gain adjuster 1560). For example, controller 1130 may
increase the gain by a factor of two, i.e., to 35 dB+6 dB=41
decibels in the illustrative example. Another preview scan may then
be done (see step 1420) using the revised auto gain of 41 decibels.
If controller 1130 determines that this gain also is too low, then
this value may be further increased by another factor of two, and
so on. If the new gain is too high, then it may be decreased based
on any of a variety of measures of the difference between it and
the previous gain, e.g., from 41 decibels to 41 dB-3 dB=38
decibels. This process may be repeated a predetermined number of
times, a number of times selected by user 701, or a number of times
computed based on the likelihood of finding a value that meets all
tests (see decision element 1445).
It is now illustratively assumed that controller 1130 succeeds in
determining an acceptable automatic gain adjustment value (see
decision element 1335). Controller 1130 may notify user 701 in
accordance with known techniques that a gain value has been
determined so that user 701 may initiate a scan at nominal
resolution (e.g., by selecting start scan graphical element 950)
using the automatically determined gain value. Alternatively,
controller 1130 may automatically initiate a scan at nominal
resolution using the automatically determined gain.
In the illustrated implementation, controller 1130 allocates a
portion of the automatically determined gain value to be applied to
emission detector 815 and a portion to be applied to VGA 815 (see
step 1350). As in the case of user-selected gains, these
apportioned gains typically are applied via an output device of
input/output devices 780 (see step 1360). If controller 1130 is not
able to automatically determine a gain value, user 701 may be given
the opportunity to select a gain value (see element 1337 and step
1307). Alternatively, controller 1130 may notify user 701 of the
situation and/or initiate a full resolution scan using the gain
value that provided the closest match with the desired pixel
distribution.
Having described various embodiments and implementations of the
present invention, it should be apparent to those skilled in the
relevant art that the foregoing is illustrative only and not
limiting, having been presented by way of example only. Many other
schemes for distributing functions among the various functional
elements of the illustrated embodiment are possible in accordance
with the present invention. The functions of any element may be
carried out in various ways in alternative embodiments. Also, the
functions of several elements may, in alternative embodiments, be
carried out by fewer, or a single, element.
For example, for purposes of clarity the functions of computer 100B
and scanner 160A are described as being implemented by the
functional elements shown in FIG. 8. However, aspects of the
invention need not be divided into these distinct functional
elements. Similarly, operations of a particular functional element
that are described separately for convenience need not be carried
out separately. For example, some or all of the functions of CPLD
830 could be implemented by process controller 740, and vice versa.
Similarly, in some embodiments, any functional element may perform
fewer, or different, operations than those described with respect
to the illustrated embodiment. Also, functional elements shown as
distinct for purposes of illustration may be incorporated within
other functional elements in a particular implementation. For
example, filters 810 and/or 820 may be components of amplifier 815,
although they are shown separately in FIG. 8 for purposes of
illustration. Also, a user may provide gain and scan data at the
same time as scan initiation data.
Also, the sequencing of functions or portions of functions
generally may be altered. For example, the method steps shown in
FIGS. 12A-C and 13 generally need not be carried out in the order
suggested by the figures. Among many possible examples, the steps
and decision elements of FIG. 13 could be included in FIG. 112C,
steps 1350 and 1360 could be combined or carried out in parallel,
and so on.
In addition, it will be understood by those skilled in the relevant
art that control and data flows between and among functional
elements of the invention and various data structures may vary in
many ways from the control and data flows described above. More
particularly, intermediary functional elements (not shown) may
direct control or data flows, and the functions of various elements
may be combined, divided, or otherwise rearranged to allow parallel
processing or for other reasons. Also, intermediate data structures
or files may be used, various described data structures or files
may be combined, the sequencing of functions or portions of
functions generally may be altered, and so on. Numerous other
embodiments, and modifications thereof, are contemplated as falling
within the scope of the present invention as defined by appended
claims and equivalents thereto.
* * * * *
References